You need to do some research. First, as stated, you will see a lot of 4 wheelers in those areas, but you should call the local DOW office and ask them about the specific area/creeks etc that you want to hunt. Are there 4 wheeler trails in that area or are they only used on jeep roads? Can you still get off road and away from the ATVs. And is the outfitter still set up in that area? These guys are a great souce of info if you ask specific questions about specific areas.
Second, both of those units are NOT draw only units only. 54 has second season OTC either sex elk tags with a cap (once they sell out, they don't sell any more) and OTC bull tags for the 3rd season. Unit 55 is OTC for the second and third season.
Here are some links to help you know if you can draw easy for the seasons that are draw (archery, muzzleloading, first rifle, 4th season):
http://huntodds.monstermuleys.com/
This link gives you lots of good info: numbers of hunters, success rates and draw odds.
http://wildlife.state.co.us/Hunting/...tatistics.aspx
And this link is the big game brochure that shows you exactly what is available in each unit (draw or OTC/bull/either sex/etc):
http://wildlife.state.co.us/SiteColl...me/biggame.pdf
All your questions should be answered with the links above and info from the local DOW people