Baddawg, If space isn't a concern I would recommend seperate units, for the same reasons already mentioned.
I would (as many here already know) recommend Garmin, they put out an excellent product, at great prices with great customer support.
As for which units, it sounds as though your a little undecided on whether or not to go with a handheld or fixed mount, if its strictly for fishing I would go with a fixed mount, if your a hunter-hiker or want to use in a car, go with a handheld, the main draw back I have with handhelds is screen size, they are small and at times hard to read.
The units you mentioned are very good "entry level" units, 1 thing to consider with them is their limited download capabilities (2.5 megs) also, the 168 you mention only has a 150 watt RMS fishfinder which won't cut it for serious saltwater use.
A great setup that would serve you well for years would be a Garmin 182 chartplotter matched up with either a 160 or 240 Blue fishfinder (500watt rms,4000 peak-to-peak), if you want a single unit the 188 is a combination unit that has a 240 blue built into a 182.
Another consideration is software/downloads, the Garmin units only accept Garmin software (proprietery) which is as good as Navionics and better then c-map and is the least expensive of the 3.
As for handhelds, the Map76 comes with all the bells and whistles (including celestial/tide tables built-in) and is probably the most user friendly gps out there.
If you can hold out on buying till mid Jan. (Boat show) prices will be roughly 10% off what you'll find in the stores now (BoatersWorld/Westmarine)
