Hi Ken,
We have used a Tomtom Go 720 for 2 or 3 years now - and it's changed our life!
Obviously it doesn't know we have a caravan on the back but, using it's "itinerary planning" facility I can ensure, before we travel, that we will approach any site according to their recommendations.
Once there the "points of interest" downloads are invaluable:
We search for the nearest supermarkets and, from the list, navigate to the one we fancy to stock up with essentials.
You can download dozens of different categories of "points of interest" and they are tremendously helpful.
I wasn't sure how much use I would get out of a Satnav, but ours has impressed me more than I imagined.
I would thoroughly recommend a Tomtom - I leant mine to my mother once and she dropped it, damaging the screen. Tomtom couldn't have been more helpful - repairng it free of charge in the fastest possible time.