Sun Valley circa 2013?
As someone from L.A. who used Chowhound exclusively until I moved to Boise (where, as you can see, this board is rarely used), I must somewhat regretfully concur that Yelp will offer better help. I would point to whatever reviewer Ru Y. recommends as he travels between Boise and Sun Valley frequently and I trust his judgment.
Restauants with adult atmosphere (several are new) - Cornerstone, Boca, Il Naso, Enoteca, B, and Vintage. Our latest favorite is Knob Hill.
Additional restauants I haven't been to: Dashi, Della Mano, Cava Cava. Good old standbys: Globus, Ketchum Grill, Sawtooth, Pioneer, Ram, Duchin Bar, Christiania. Cristinas for breakfast and lunch.
Only some restauants have full liquor licenses, others are only beer and wine.
You should look at Yelp for current reviews. Hope this helps