Hiked this with my 12 year old. Although there are a few trip reports that are pretty recent, I thought I'd write our experience:

Road: Yes most reviews I read recommended taking Forest Road 25 and then Forest Road 99. I took Forest Road 25 and then took a right on a connector gravel road (after Iron Creek campground) to Forest Road 26, and it was not that bad. It's a paved road with patches of gravels and some dips here and there. I am sure NF-25 would be a better option, but NF-26 was not bad either. There was also no road construction work that Sunday.

Trail: It was definitely not busy when we started at around 1:30 PM on Sunday. There were many parking spots at Windy Ridge parking lot.

The trail started on a gravel road with no shade, but offered a great view of Mt. Adams and of course Mt. St Helens right in your face.

The trail was easy to follow with only few stream crossings. And yes, views of Lupine started to show after we hiked in for 2.7 mi, just before the first stream crossing and the first trail marker to Abraham Trail, Loowit Falls and Loowit Trail. The views got better and better when we saw Spirit Lake on our right.

The trail was pretty gentle for my 12 year old who loves challenge. So I think this hike is great for kids even if you did not make it to the Falls. There's a water source (like a mini falls) on Loowit Trail in case you need to filter some water. 

The lupines still looked gorgeous but maybe will look better after the rain on Monday.

The whole hike was so pleasant with constant breeze that I did not feel the heat. I did not hear or saw any mosquitoes at all during our entire hike. There were bees, butterflies and other bugs but they were very light and did not bother us.

There were not many people on the trail. In fact we mostly saw people who did the Loowit Loop, and we saw no one at the Falls. 

One of the highlights was the herd of Mountain Goats chilling out on the hill near the Falls. There were at least 20 of them.

With the open view, this hike would be so great for sunset. You'd hike in solitude and when you finished the hike and headed home, you would encounter less cars from both directions.

Total mileage: 9.2 mi  out and back.

Total time: 4:51 (12 year old's leisure pace with plenty of photo stops and a 15 mins lunch break)

Take FR-25 to FR99 from Randle (from the north). At the entrance of SR 133 the signs will tell you that FR25 is closed at milepost 23, which is true, but the intersection with 99 is before that closure, so you can still make it to Windy Ridge Viewpoint where the parking lot is (Google Maps will insist that you take FR-26; I don't recommend it) The road is in pretty good condition, with just some mild potholes; any car can make it. There was no construction work on this Saturday; you just have to drive carefully through the areas being worked on. It took us about 4 1/2 hours from Seattle, including bathroom and gas breaks. There was plenty of space in the parking lot.

The bathrooms at the trailhead were closed today. If they're still closed by the time you go, the closest alternatives are at the Smith Creek lookout about 1.5 miles up FS-99.

The lupine is definitely starting to dry up in places, but it was still very lush in many areas, most notably the Windy Trail right before the intersection with the Loowit Trail (i.e. east of the intersection); see the attached map. It smelled heavenly. Other flowers were paintbrush (sometimes in large patches), yarrow, Oregon sunshine, penstemon, orange agoseris, Siberian candyflower, and invasive oxeye daisy and St. John's wort. The phacelia and partridgefoot have dried up for the most part; aster is just beginning to bloom.

The first 2 miles on the gravel service road were a gentle grade and easy walking. It gets a little bit steeper after that, but it's still not bad and it's well maintained. We went a bit past the intersection with the Loowit trail (about 3 miles in) before turning around. It was 75 degrees with occasional wind, but it still felt pretty hot and there was no shade. We left at 1:30 and were back at 5 pm (at a slow pace for picture-taking). Bugs weren't too bad as long as we kept moving.

Lupine Super bloom was spectacular, out of this world

Detailed trip report is in youtube vide, this site isn't letting me upload most of my images to size limit.

Great views and beautiful fields of flowers

Did the plains of Abraham loop to windy pass, and then added Loowit falls, for a total of ~11.5 miles, 5.5 hours of hiking

The trail is mostly good, though some narrow sections on plains of Abraham, narrow & steep but still doable section near windy pass, and couple of steep sections on the way to Loowit falls.

Drove through FS 25 and FS 99 till it's end. There is ongoing road work on FS 25, one lane is closed and the other may be blocked while work is going on during the day. I waited several minutes, the sign says up to half an hour wait is possible. Otherwise the roads are all paved (except very short sections) and very winding.

We started our overnight from Ape Canyon trailhead around 10am heading towards Pumice Butte. Nice and cool in the woods for the first few miles. Views of St Helens and Adams from the north side of the butte, where we set up camp. After hanging out for a bit we set out for Loowit Falls.

Passing through the Plains of Abraham you're treated to great views of the aforementioned mountains and a beautiful Mars-like environment. I would say after this was the highlight of the trip - upon hiking over Windy Pass it really opens up. Incredible views of Rainier, Spirit Lake, and Mount Margaret backcountry. The area is bursting with purple lupine and we were blessed with the presence of a very large herd of goats. After checking out the waterfall we headed back to camp while taking in the golden hour washing over the landscape.

In the morning we watched a family of goats playing before we ate breakfast and packed out. Overall this makes for a lovely overnight with great options for side trips.

Beta: No snow on the trail. A bit of water nearby camp on the N side of Pumice Butte, but I doubt it will be there much longer. If my memory is correct about 2.5 miles down the Loowit Trail (all flat) before you reach Windy Pass there is a running creek of clear water, and we definitely passed several strongly flowing water sources after Windy Pass. Navigating up and over Alpine Butte - it can be hard to find the initial trail, but there is one that doesn't involve going straight up and over. This part of the trail a little slippery and narrow in places. No mosquitos for us but a few pesky biting flies in the woods.