I've used LT parking 3x. It's o.k. Not the fastest shuttle wise but I haven't used anyone else other than some outfit under the Oak Street bridge in Vancouver just once. You can self checkin for selected airlines while waiting at the bu stop if you haven't web checkedin already. I do believe the AC miles requirement is a minimum stay of 4 days.

Depending on where you live & time of travel, getting a taxi may be more convenient at slightly-greater expense.