smoked a few cross rib chucks here...very good choice for pulled beef, as the marbeling helps the muscle groups loosen up and stay moist towards the end when temps get close to the 200* mark.
As Ross mentioned, you can go pretty simple and basic with beef for seasonings, as the meat's natural flavor will carry itself very well. I have used some fairly complicated dry rubs on beef, and then on occasion, I've gone the KISS method with garlic, salt & pepper. For the pulled beef sammies, if you can put a drip pan under the chuckie, but still keep the meat elevated off the pan with a roast rack, or, put a pan under the cooking grate, then add some chopped onion, minced garlic, cracked black pepepr and water to the pan, you'll catch all those great natural drippings from the meat. You can defat the liquids while the chuckie rests before pulling and build yourself a gret au jus...better than any sauce you'd want to use, and alot easier to bring it all together. Just toss some instant coffee into the defated juices, mix, heat, then toss the pulled beef in and enjoy!
For smoke, a bit of sharpness from hickory is good for beef along with cherry/pecan. Cherry is a heavier fruit flavor and aroma, while pecan has more of a mild pungent aroma with a slightly nutty, sweet background flavor. I've never had the opportunity to use maple, but I imagine the flavor and aroma would be nice as well....I'm thinking about maple smoked bacon right now...damn good stuff!
I don't mop, baste, or spritz very often myself, but if you have a horizontal smoker and no way to use a water pan, then, it may be a good thing to do. I've also read that the application of cold liquid increases the cooking time quite a bit, along with loss of chamber temp from opening the smoker up, so, it's sixes, IMHO. Oh, if a no-foil smoke is your game for the ribs and/or chuckie, the mop should help with final moisture content, also.
Have a great smoke!