I'll just mention where we flew on Southwest this year and where we are flying on Southwest next year // I am big on direct flights too and that influences me a bit - more appealing to go to places I can get to easily, but loosing our hub airline and Southwest being our largest carrier means we have more limited choices than we used to.
This Year:
-- Newark/LaGuradia -- If you are into cities, NYC is pretty cool. The theatre scene there is amazing. There are other cool city things to do there too. But hotels are very expensive. We had such an inspirational amazing theatre stay, though, and I am even planning on going again next year. For budget reasons (hotel prices and Broadway ticket prices) my NYC stays are short. I have relatives that I visit in New Jersey annually making this a more obvious choice for me than it might be for some. I have found great reasonable SW flights here.
-- Fort Lauderdale. -- I'm not really a cruise person, but if you are into cruises (kind of nice to go lots of places and not pack/unpack, have all your food and entertainment taken care of, and go a few different places). Also who can fault the crystal clear waters of the Caribbean, Southwest flies here, and it is a major cruise port. It's not the same as really exploring a place, though, but it's all about what appeals to you and your family. Many in my family and some friends absolutely adore cruise vacations.
-- Denver -- For us it's the closest affordable place to fly to for mountain access. Estes Park/Rocky Mountain National Park two hours from Denver is my favorite. I typically do one night in Denver to acclimate to the altitude a bit and then head to the mountains -- Mountains are the reason to go there.
-- LAX (Los Angeles) for LA / Hollywood /
Disneyland -- It was worth doing once, but I prefer the choices above to this. Traffic is crazy there. It's a crowded place. Loved the original Disneyland theme park though - just charming
Next Year:
-- Phoenix -- Sedona, AZ (Red Rocks are beautiful) and it's a great place to go two hours away from that airport. We are having an extended family group go there next year for a week. We have three condos booked next to each other. We'll stay in Sedona the whole time, enjoy stuff there and do a few days trips -- short day trips to nearby Indian ruins and one long day trip to the Grand Canyon for those who have not seen it before (long way -- three hours each way), but with a whole group surprisingly I have actually enjoyed the long day trip and not minded the driving. It helps I'm sure that all other stuff we are doing that week is close by with minimal driving or I probably wouldn't be as positive on that.
FYI -- I am actually booked to go to Key West next year, but I'm flying there directly, and that's not on Southwest. Flying to Fort Lauderdale and driving down when looking at rental car costs and time was going to be way more expensive than just flying another airline direct. Fort Lauderdale would have been my option on Southwest. The drive down though is pretty cool and we will miss that. But it's not exactly a short drive. With Irma who knows what damage will be/if rebuilding will be required. That could affect this area. Also, hotel prices in the Keys high season are as bad as hotel prices in NYC. This meant my Key West trip is more of a mini trip than an overly long vacation.
NYC is going to be a mini repeat next year too, as mentioned above.
******************
Lots of people love it, but I'm not a huge fan of Las Vegas -- some great shows, but kind of expensive and not that much to do IMHO if you are not into gambling and bars. Zion National Park and the charming gateway city of Springdale are three hours away, and Vegas is the best place to fly to, to access that. For me a combo stay of those two could be appealing.