Jim,
Get on the Garmin website they have a brilliant sat nav finder page. All you do is key in the functions you want ie blue tooth, euro maps, itinerary etc and it comes up with the models and prices available. Wish I had found the page before I bought mine
Timbo had a Tom Tom and I had a Garmin on our little escapade and we reckon between the two of them we could have made one good Sat Nav

His you could store an itinerary on (ideal if you don't want to keep adding locations as you go) and mine had all the fuel and hotels and how far to each.
Next time I get one I'll put a lot more thought into the features I want. I wouldn't go bike specific either, way too expensive. I'll send you a pic of how mines set up if you like. Just chuking one in a bag and putting it in you tank bag is a pain in the a$$ when the sun's shinning, the angles all wrong and all you see is reflections.
Oh, ran mine off a ciggy lighter from halfords (£5-99) and just chucked it under the seat in a ziploc bag.
Pete.l