I've owned two gassers and one DP.
Our first gasser, a 2004 34' National RV SeaBreeze drove like a pig. I think the Workhorse chassis contributed a lot to that. We tried a long trip once and regretted it. So we stuck to driving in state (WI) for the 7 years we owned it.
Our first and only DP was a 2001 Newmar Mountain Aire with a Spartan chassis. We spent several years full timing in this rig and the Newmar's ride, handling, fit and finish were very good. On the other hand, let me say a word about maintenance . . . Very expensive. The 350 ISL Cummins needed a head replacement for $10K and later because the engine tended to run hot, we decided to replace the radiator and charge cooler for about $4K.
Our second and current gasser is a 23-year-old 2001 V10 National RV SeaView. We bought for about $30k because of its very low mileage. It drives like a dream. We were extremely surprised at the ride quality because of our first gasser experience. We live in the CA Sierra foothills so we're no stranger to mountain roads. Last year we drove to Pennsylvania (~ 7,500 miles) towing our Jeep Wrangler, and it was no big deal. This summer we're going to Washington state and in fall a trip around the Eastern Sierras.
OP, while it's generally true a DP is "better" than a gasser, there are trade offs. Expense being one. Unlike what Onyrief said, we actually "upgraded" from a DP to a gasser. Don't be fooled by all the generalities being tossed around here. Just make sure you drive before you buy -- and make sure you log some freeway miles in that test drive.