We took a guided boat trip to the other side of Lake McDonald and thought that was well worth it. The hiking is awesome on all the trails we trekked although I don't remember which ones they were. I think you'd be hard pressed to find a bad one. The whole area is amazing. Canoeing and kayaking are also awesome in the smaller lakes, but it's probably too cold for that right now. I don't remember much about the food in Kalispell. We mainly just ate breakfast at some random cafe and packed food for the rest of the day. Our trip wasn't well planned. A buddy of mine called me up one day and offered to pay for the fuel if I'd fly him to Polson, so I took my daughter and we visited the park for a few days. It probably would have been better had I planned more, but we pretty much just showed up and it still was a great time. I'd like to go back someday.
One thing I remember about the park is it wasn't at all crowded like many other national parks. The roads were a little congested as many people like to just drive through, but the park itself is quite nice. You do see other people often on the trails, but they aren't too busy and if I remember correctly we were there sometime close to peak season.