Grand Sierra has remodeled their property. They have a nice new sports book that's pretty classy, a new night club that features an indoor pool in the night club. Plus they got stuff for kids there, like go carts, miniature golf, bungee drop.
Peppermill and Atlantis are still my favorite though, they both have great health spas for the wife, and Peppermill still has the nicest sports book in town. Tahoe is beautiful and great during the summer, lots of stuff to do at the lake like parasailing, ect. The gambling sucks there though for black jack: 6/5. If you want to play blackjack you should stay in Reno, Tahoe's only a half hour drive if you want to go to the lake. Peppermill has a nightclub called "Edge" which is pretty happening on the weekends. I never really go down town just don't care for the atmosphere, unless there's an event going on.
You should check out Virginia City while you are here too. During the gold rush Virginia City was once home to the most millionaires per capita in US. All the old mansions are still standing, some cool museums visit, and the town still looks lik the old west.
If you're coming in August book early because, the "Hot August Night's" event is going on, and people come from all over the world with their classic cars and everyone sells out.
My top choices would be,
1. Peppermill
2. Atlantis
3. Grand Sierra
If you want to stay down town I'd go with, Silver Legacy or Eldorado.
Downtown isn't as bad as it used to be, after 2006 many casinos down town went under, but most have reopened. One of them reopened with no gambling at all, and the building is now for rock climbing on the side of the building, if you're in to rock climbing.
Montbleu in Tahoe has good entertainment, bands like the Beach Boys, and Comedians like Daniel Tosh.