I just returned from snowboarding at Jackson Hole Mountain Resort (3 days) and Grand Targhee (1 day). I was on the mountains from 1/20-1/23. I really enjoyed it. There was no fresh powder, which was the only downside, but they were getting dumped on on my return day.
Background: I am an upper intermediate boarder. I was doing mostly double blue (their name for blue/black) groomers, a few blacks, a few bowls, and some woods (I would have done more off trail, but they hadn't had fresh powder for 5 days). I am 5'10", 11.5 boot, riding a 2010 Gnu Rider's Choice MTX (camber) with Ride SPI bindings, and Saloman Malamute boots.
I have to tell you, in 4 days, I never waited for a single lift more than 15 seconds. There is no one there, and there are no lines.
Here are my thoughts. This is sort of a stream of conciousness.
Jackson Hole is awesomely steep. Everything is steep. The traverses are steep (no chance of getting stuck, big chance of falling off the mountain). The mountain was very well groomed. I really enjoyed the new Casper lift area, which is all superfast/superwide groomers (I went 47 mph if you want to know), with excellent high speed quad service.
Apres Vous lift area was also fun, with a variety blues and ok blacks. I enjoyed the tighter slopes there, but that area was a little more crowded (it was referred to me by a lift operator as the "tourist" area).
Thunder Chair area was my favorite. Laramie Bowl was my favorite run. It felt like I was boarding down the Hoover Dam, fast/steep/concave bowl. I think at most mountains this would have been a black, but JH has a pretty serious bent towards steep slopes.
Rendevous Bowl: I tried it. I boarded the bowl in the single black area. It was heavily mogulled out, which I don't really like, but I pulled it off. Glad I did it, but a bit tough for my skill level.
Least favorite run: South Traverse coming back from Rendevous Mountain. A narrow and steep crossover that switched back 3 times. I usually complain about flat cat track traverses. This was the opposite.
Side Note about Grand Targhee: I took a day trip over to Grand Targhee (I had a rental car). It took me about 45 minutes to drive there in good weather conditions. Grand Targhee is like a smaller version of Kirkwood (I mean this is a very good way). It has 2600 acreas of skiable terrain, but only 3 chair lifts. You can go anywhere. Not may trees, and lots of fun places to ski in the trees. There were maybe 100 people on the mountain that who day (a Tuesday). Think about that math. I rarely saw other people except when skiing into the lodge area. The terrain felt much less steep. I was doing mostly blacks and woods skiing there. I highly recommend a day trip over there if you are at JH.
For Reference: I rented a condo at Teton Village through VRBO and rented a car through Priceline (I highly recommend this). I drove into Jackson most nights for dinner. Dinner at the Local (awesome), Snake River Brewing Company (very good), Mangy Moose (in Teton Village/Good), and Gun & Barrel (good). Desserts at CocoLove are amazing, and everything at the Bunnery was awesome for breakfast and dessert.
I hope this helps you when choosing a future trip.