I've never had a pit bbq, but it's something I'm really interested in doing. My next endeavor will be to build an outdoor brick oven/fireplace. Most of my bbq'ing experience is with indirect fire and lots of hickory, apple, or cherry wood smoke. My go to meats are also leg of lamb, ribs, tri-tip, salmon, any & all types of pork, and turkey breast (which makes great sandwiches). I'm a huge fan of rubs and homemade sauces. I cannot recommend the book Herbs and Spices: The Cook's Reference enough. It is less an recipe book and more an instructional on spices and what to do with them. I use it to make curries and spices mixtures a few times a month.
While we're on the subject, good quality spices are paramount for any of my rubs. Penzeys has been a family tradition for prime, bulk and hard to find spices for a few decades now.