I would suggest one of the Garmin Mapping units. They come with a Base Map of N. America. (Canada, USA, and Mexico) The base maps are short on detail, and for coverage USA, and Canada rank best but you want more then that. You have a lot of options.
I am currently loading a 4 GB Micro SD card for my 76Cx with City Navigator. This software package covers all of Canada, USA, including Alaska, and Hawaii. I prefer the 76Cx over the excellent 60Cx which shares the same operating system. The difference is the 60Cx sinks, and the 76Cx floats.
In addition I am loading Topo 2008 maps for the West Coast on the 4 GB card. There is a map limit which the 60Cx and 76Cx series can work with, it is 2025. I guess covering the US, and Canada once, and then covering addition parts with Topo maps is okay.
I prefer to buy the software on a DVD and build map sets on my computer and transfer it to a micro sd card.
A top of the line Garmin Oregon t comes with preload US Topo maps and you can load a card with City Navigator or load City Navigator on a micro sd card. For some reason it is not listed on the list for pre-loaded factory micro sd cards.
What I would do is by 60Cx
http://www.tigergps.com/garmingpsmap60cx.html and purchase the pre-loaded City Navigator micro sd card. It has all the maps covering the U.S. and Canada.
If you are going to be out on the water I would buy the 76Cx and it takes the same pre-loaded card.
http://www.tigergps.com/garmingpsmap76cx.htmlI have a top of the line Rino 530Cx 5 watt radio. It comes with a base map and other mapping products and can be added. Treat it the same as a 60CSx or 76CSx. It is illegal in Canada. Garmin makes a special 2 watt model for Canada
The older Rino models, the 110, 120, and 130 do not have the high sensitivity receiver. I would not spend my money on them. They are a good open country unit.
The CSx models offer a compass, and an altimeter. Unless you have a weather station to collect the pressure the altimeter does not buy you much. The electronic compass is nice. But you can make do nicely with the gps compass in the unit.
Caution when buy gps units at local outdoor stores you will pay an extra $100 in most cases. Wal Mart .com has some good gps sales. Wal Mart has the baseline Nuvi on sale for $109.00. It has US and Canada maps.