With gauges there are really two schools of thought for recreational diving - bottom timer only or computer-generated decompression monitoring (for recreational diving).
Bottom-timer-only diving uses a couple different ways to keep track of staying within no-deco limits for recreational diving. The practice is used by many people on this board and it generally starts with a "starting point" of time and depth, and then easily allows you to make adjustments as your dive dictates. It also works for any gas with a couple easy adjustments. There is a great article about how it's done here:
http://dir-diver.com/en/knowledge/min_deco_table.html If you were to decide bottom timers are the way to want to go, you can often save a lot of money. There are some bottom timers now which allow you to download your dives too.
Computer-calculated/monitored deco (or no-deco-limits) is the other school of thought. This is where you follow the instructions of your computer and/or stay within the "bounds" of no-decompression time as the computer tells you. I agree that if you're going to purchase a computer, buy one with nitrox capacity. Nitrox is definitely mainstream now and has almost made air-only computers obsolete. I agree with Lynne that air-integration is unnecessary, and can be a hassle, but others have the opposite opinion. It does add a bit more complexity and set-up, but it's also convenient to have your pressure on your wrist where it's easily viewable. On that note, I also much prefer wrist-mounted gauges to console ones.
Interface is key - having a computer you can actually use, and practice with when you're not diving to ensure you're proficient with it, is very important. Some computers are very intuitive and others can be rather challenging to operate. The best thing to do here is to try them out yourself.
Readability is also key - you've got your gauge to provide you with information, so make sure you can read that information. Back-lit gauges are helpful, large numbers and font are really nice, and the entrance of OLED displays has really taken readability to the next level.
I have several different computers and bottom timers you're welcome to try out - in fact, we can take them all down for a dive at the same time so you can see them side-by-side. You can play with them at the surface and then do the same underwater. I do work for Liquivision Products, a company that makes dive computers and gauges, but I'm happy to show you several different options and will try not to be too biased.
Shoot me a PM and let's go diving.