Long, but here goes...
Hayes, I'm in the same boat as you. I want a good "on road" GPS for city/hwy navigation, yet I also want a good "off road" GPS for topos and such. I've been doing a bit of research on both and have decided to focus my attention to Garmin products either way I go.
Here a few pros and cons I've found w/ handheld GPS models (designed more for off road use) and larger, in car GPS models (designed more for on road use). Again, these are just my opinions based on the Garmin models I've researched.
Off Road GPS:
Pros:
Compact/handheld, rugged construction & topo map navigation. Often these units have a stronger antenna to pick up a signal in heavily wooded areas and deep canyons.
Cons:
Small display, no voice commands offered (only "beeps" are given when told to turn at street corner), and poor city/street navigation. In order to add the nice city/street nav software, you're looking at an additional $100 or more. You still don't get voice commands, but you get very good city/hwy street maps for all of North America.
On Road GPS:
Pros:
Large display, great city/street nav maps, voice prompts and some are slim enough to carry in your pocket. These units do not have a rugged design, so you must be careful when carrying them in hand.
Cons:
Mainly, no topo maps. As soon as you pull of the road, the GPS gives no explanation of the area your in. These units do not always have the best antennas either - Poor signal quality in heavily wooded areas. Again they work great as long as you are on the road, but once you get off, watch out!
With that said, I'm leaning more to getting 1 of each
. One for off road and one for on road. If you decide on just one, you really have to weigh your own pros and cons of each. However, those are mine.
As far as
Off Road GPS goes, I've been looking at 2 specific handheld models by Garmin. The first being, the Garmin Colorado 400t. This is latest and great handheld Garmin has released. The display looks more realistic than ever and the controls have been upgraded. Although, the cheapest I've found it is $520...and that's without the city/hwy nav software. I'd be looking at around $650+ to purchase the unit, nav software and other misc items for it. Ouch! Check it out here:
Colorado 400t. (Garmin's home page list the unit for $640, but you can find it much cheaper at other sites.)
They also offer a few other versions of the Colorado, as seen here:
Colorado Comparisons, but only the 400t has the topos you really need.
The 2nd handheld I'm looking at, is the Garmin GPSMAP 60CSx. They also offer a model called the 60Cx, but for $40 more, why not get a few more options and get the 60CSx. These units are not as "cool" as the new Colorados, but they have been around long enough to have a proven track record. Check it out here:
GPSMAP 60CSx. (Again, Garmin's home page list the unit for $430, but you can find it much cheaper at other sites.)
For a comparison of the 60Cx and the 60CSx, check them out here:
60 Series Comparison.
The good news is, the Colorado is supposed to replace the 60 series units, so the 60CSx will continue to drop in price as months follow. I've found some dealers carry the 60CSx for as little as $250.00. Granted, if you want the city/hwy nav software, you will need to add that too. I believe Garmin sells that for around an extra $120 or so.
As far as
On Road GPS goes, I'm really impressed with the Garmin Nuvi Series. Any model in this category is a great "on road gps" IMO. However, for the money, I especially like the Garmin nuvi 200W (W stands for widescreen) as seen here:
Garmin Nuvi 200W. (Garmin's site has it tagged at $320, but by searching online, I've found it for $200.) I like the fact that if offers voice turn-by-turn directions. This is a huge plus while driving. The large display is very accomodating as well. It also has tons of POIs (points of interest). The unit is touch screen too.
For a comparison of the Nuvi models, check them out here:
Nuvi Series.
Again, all the Nuvi models are nice, but for the most "bang for your buck" I'm really impressed with the 200W.
As it stands now, with the price of the Colorado's as high as they are, I'm leaning more towards purchasing the 60CSx and the Nuvi 200W for both on the road and off the road use. Both can be had for under $500...which is not bad at all for 2 GPS models. I do like the thought of adding city/hwy nav software to the 60CSx, but I believe I would rather have a larger display and turn-by-turn voice directions for a in car GPS.
Your needs may be different, but I thought I'd share what I've come across thus far. Good luck!
EDIT:
I've recenlty been doing more research on the Garmin Nuvi series and have come to the conclusion that the Nuvi 750 blows the 200W out of the water. For $200 more, it's definitely worth it to upgrade to the 750. For on road use, go with the 750...you will not be disappointed. It is without a doubt the best bang for your buck.
I could type out all the pros of the 750, but it would take too long. Just go to garmin's site and check out the 750. Compare it to others and see what you think. (Garmin has it priced at $590.00, but I've seen it online for sale for $400 w/ free shipping.):
Nuvi 750 & 200W Comparison.