I second the suggestion above to have at least 4 kegs if you have a 2-tap system. That way you'll always have beer ready to go when one keg kicks. You might also think about your space limitations at home, and how big of a system you want to do. Will you be using a refrigerator? A chester freezer? I have a 3 keg keezer, which is about perfect for me. It seems to be the sweet spot for variety and quantity in our household. (whenever I get bored with my beer, we hold a happy hour, and clear out a ton of it with the help of some friends! I'm at the point in life where I really don't need to finish a 5 gallon keg all on my own).
A keezer is really handy in terms of footprint and appearance. We have it in a corner of a smaller room, where the top can double as a table. The main disadvantage that I have found is that it takes a bit more effort to lift kegs in and out of the keezer--if you have back issues or strength limitations, that would be something to keep in mind. Also, it's really hard to clean on the bottom of the unit. Fridges are bulkier, but way easier to access. Before you buy something, get some cardboard cutouts of your keg bottoms (or an approximation), and test them out to make sure everything fits. Check height carefully, too. Full kegs are heavy, so make sure that if you do a fridge that the shelf the kegs sit on can support them.
Another decision is ball lock vs. pin lock...I have a pinlock system, which is great for me, but most of my brewing friends have balllocks, so it makes it annoying if we want to share kegs or if I want to bring a keg to a brew club event.
You don't need to do this right away, but I saved my pennies and got a second CO2 cylinder. This means that I can carbonate stuff outside of the keezer, so that the keg is all ready to go whenever it's needed (minus a cooling/settling period after movement). Also, if the cylinder in my keezer runs out, I can just swap it out immediately (very handy if it happens at a time when you can't get to the gas supplier immediately).
Depending on your system, I would recommend at least 15 feet of beverage line per tap...I started on the shorter side (~10 feet), and ended up having to go longer (and hence ended up with tubing lengths that weren't at all useful).