Don't Go all the way to wilsonville for a hotel. if you head in towards portland on the 26, there are plenty of hotels from government camp to welches. Personally if you're going to a lake in the mountains you should be CAMPING. And there are plenty of sites to do so, both reserved and not. There are great hiking trails and it's also full of fish and crawdads. Boating is a must if possible.
This lake is so wonderful. La Quinta Inn Wilsonville is a
nice place to get some rest, and if by chance you have a boat, Waverly Marina is a good marina. Krause Springs is always fun to check out; a tremendous zoo close to Timothy Lake is Oregon Zoo; they have scores of lovely animals.