I've not marinated a chuck prior to smoking yet, so can't say what would be a good way to go for that route. I dry rub most all my beef, but for the most part I base the salt content of my rub on how much interior fat the cut has...more fat = more salt. Salt draws out water out, and this seems to help breakdown fat. The flip side is, heavy salting of lean cuts can cause some dryness to occur.
A dry rub I used recently which has a bit of heat and develops a great bark is found here, if you want to look it over:http://www.smokingmeatforums.com/for...threadid=82939
For a look at it in action on an English and a Chuck, look here:http://smokingmeatforums.com/forums/...ad.php?t=82944