Oh geez. I never had to stay in a hotel there before, so I'm no help. There's not a ton of scummy places though, so you should be fairly safe. Hubby says the Hampton should be really good.
Saturday Farmer's Market in downtown rocks. It's 8am-noon I think? The flagship Tri-State is there on the Moscow-Pullman Hwy. So. much. fun. Well, at least for me - camping, cooking, clothes, great shoe selection, it's just fun.
There's a water park there somewhere, I can't remember the address. I remember old coworkers taking there kids there and loving it on hot days.
There's a groovy co-op that's like a little Trader Joe's - cute, but expensive.
Eating... well shoot. All my old haunts have since closed up. I think one Chinese place *might* still be there.
The mall's back up on the upswing and has very few vacancies (was practically half empty at one point in the last 10 years). There's a lovely game/computer (nerd) store there in the mall that I'd say is pretty trustworthy. :)
Walking around campus... the lawn up by the Admin building is very pretty, and things should be fairly nice and leafy this time of year. The cows in the Ag dept may be worth looking at if they're out on the pasture by the road - some of the cows have glass stomachs (I think it's UI, not WSU, but I could be wrong - I know WSU has the bears and Ferdinand's ice cream and so on). There's also the UI arboretum, a fun walk. Beware of couples, uh, coupling there, if you take the little ones.