I'm considering a GPS unit for my bicycle. I'm wondering if others are as well.

Here's what I'm thinking. Last year, on my tour along the Northern Tier I missed a couple turns and rode past one potential campground. Missing the turns meant I stayed on the main highway - lots of traffic, no shoulder - instead of pulling off onto one of the bucolic backroads that ACA routes prefer. When I missed the campground I ended up in a motel, and I was lucky to get the last room because of a softball tournament in town.

• I want a GPS on which I can enter my route in advance. I understand you can download the GPS data for the ACA routes from their website. That would be a must, because there are several ACA routes I want to try in the future.
• I want to be able to change my route on the road. In other words, I don't want to be dependent on my home computer to enter routes.
• I want to know where restaurants, grocery stores, campgrounds, motels, historical attractions, bike shops, etc. are.
• I want it to work under a tree canopy. (I had an Etrex I bought for my kayak. When I took it backpacking it had a lot of trouble receiving a signal in the woods.)
• I'd like to have an altimeter. I'd like to be able to download my routes onto my computer after I get home and have a display of the elevation. This isn't crucial, but it would be fun and interesting.

I've looked at the Garmin Etrex Vista HCx, the Garmin GPSMap 60CSx, the Garmin Oregon, and the DeLorme Earthmate PN-40. I've also looked at the Garmin Edge series, but they don't seem as well suited to a tourer, and the one with mapping is awfully expensive.

Any thoughts, anyone?