If you aren't opposed to sitting on the bus for a while they will definately get you back to the airport on time....
SW flies out of Terminal A and DME stops at terminal B first (but even with a full bus and most people getting off at B we were there less than 5 minutes) and then go to A....from there you just get your luggage from the bus, take the escalator (or elevator) up to the ticketing level and turn left....SW is a short hike down from there.
If you already have boarding passes (the hotel guest services desk will be happy to print them out for you the day before so you can get an A pass) then you just go to a kiosk and put in the info to check baggage (takes 30 seconds) and there is rarely if ever a wait at SW anymore since they have so many kiosks (you do NOT need to stand in line for check in....I think people just do that because they think they are supposed to or something....there were probably 30 people waiting in line and there were at least 10 kiosks open!! You can do the same thing at both places)....they will tag your bags for you and have you take them over to security....entire proces = less than 5 minutes and you are off to the gate.
So even if you make some stops after the DME pickup at your hotel you will have plenty of time to make your flight. My complaint was they picked us up almost 3.25 hours before flight time (but then we were on the bus a little over 2 hours before we got to our stop at terminal A...I think we were a worst case scenario)...and still had plenty of time.