The wife and I live full time in our RV and we move around a lot. Most of the RV parks we stay in offer wireless but a great deal of them don't offer GREAT wireless. If you aren't parked pretty close to the "clubhouse" or "office", where they frequently host their wireless signal broadcaster, you might get such a weak signal that you can't connect at all.
One solution, and an easy one that frequently works, is to acquire an external antenna for your laptop. They are fairly cheap (less than $40 at Walmart), and install easily by plugging into a USB port. They also self-configure for the most part. Cisco makes one called the "Valet" that is super easy to use. I also have a Linksys N USB device that is fairly easy to use, and although it's a little more pricey ($80) it has better reception with 2 external antennas of its own.
But sometimes even that won't do the job. In my "box of tricks" that I packed when we moved into the rig, I have a couple of wireless routers. One of them is a Linksys WRT350N. For this configuration, the factory firmware (or operating system) doesn't have the configurability or performance, so I replaced it with the latest firmware from DD-WRT (
http://www.dd-wrt.com). They have an extensive Wiki, accessible from their homepage, on how to get the free download and install or "flash" it onto the router. Once you get dd-wrt installed, the rest is pretty simple. Unless you want to get fancy and install a 36" external mast antenna on the outside of your rig. In that case, you could probably get a signal from a Starbucks up to