Mike,
When picking a pit, WSM, side-firebox, ECB, UDS, firebricks inside a weber kettle, BGE, whatever; Each of those pits has different characteristics that make it stronger in some areas and possibly weaker in others, but it really comes down to how much you're going to use it, how much you want to spend to get it and spending the time to learn your pit after you buy it or build it.
Don't let the idea of having to modify the pit slightly deter you from one or the other, with the possible exception of the BGE, any of those pits, including the WSM, could need tweaking or modification coming out of the box. It's not a big deal.
All that being said, I would say get a Weber Smokey Mountain (AKA: "WSM" or "Weber Bullet"). The level of user product support is relatively unmatched.
Take a look:
http://www.virtualweberbullet.com/cook.html
They walk you completely through the recipes, all the way down to the vent positions over the entire length of the cook so that you will only have to make minor adjustments.
You can also do relatively unattended 12+ hour cooks right out of the box:
http://www.virtualweberbullet.com/fireup2.html#minion
Look, let me put it this way, if MACS can get one and turn out good bbq with it, than anyone can.
One thing about WSMs, they are meant to burn charcoal. Either briquettes or lump, and you add chunks of smoke wood to the mix (a little bit goes a long way in a weber). If you have a large supply of free fruit or nut wood or hardwood that is good for smoking, then maybe you should consider a SFB (Side FireBox) because you can burn "logs" (cut wood) in them. They do require more attenttion when than WSMs though.
Also, the SFBs are better at adaping back and forth from being a smoker to being a big grill. Not that the WSMs can't be used as grills, just that the SFB has a bit of an upper hand when it comes being used as a grill.
If you go with an SFB, take a look at a Char-Griller with the add on firebox. You might need to make some mods to the coal basket though. But they are very simple mods.
Don't confuse Char-Griller with Char-Broil. The Char-Broil SFB units are very thin and junky.
