The Cabelas store in Post Falls is pretty easy to spend some time in. Really your only choice of GA-friendly airports is either Felts Field (KSFF) where there are a fair number of RVs, or Coeur d'Alene (KCDA). Rental cars should be accessible from both airports. Actually KCDA is probably closer to the Post Falls outlet malls and Cabela's, plus it's the closest to downtown Coeur d' Alene and the (4- or 5-star) Coeur d'Alene resort. If a wife likes to be treated, the Dockside Restaurant at the resort is pretty nice and affordable. And, since you mentioned it, there's a Olive Garden Restaurant on Hwy 95 just near the east side of the airport too. If kids are involved, the Kroc Center (swim center with water slides) is worth a couple hours of time.
There is no longer a field at Silverwood as far as I know. Unfortunately, once the amusement park came to what used to be an aerodrome, and then grew larger and larger, the public use field was closed. Silverwood is probably closest to Coeur d'Alene, but is probably within 45 minutes of Sandpoint as well (another good summer/winter destination).