I stayed at the Hilton last summer with my 3 DS. Yes, it does cost you about $10 - $12 to self park, but you do have in and out privileges.
The buses come every 30 minutes and they pick up for ALL of the DTD hotels. However, it goes very quickly since the buses pull up, load the passengers and then they are off. Like all of the buses, they do become quite packed at the end of the day.
Also, sometimes the pick-up and drop off places are different at the parks, so be sure to listen to the driver. We did try the DTD buses, but those came at odd times so we couldn't really plan on how long we were waiting...
We enjoyed our stay at the Hilton, close to DTD so I could go shopping and my teenagers spent time at DisneyQuest. They returned back to the room at their leisure.
We had a junior suite for the 4 our us. It was pretty tight with the sofabed pulled out, but we had two sinks, one outside the bathroom/one inside and this was a helpful perk.
I would stay there again. If you have a Signature Visa, keep checking the website for the special discount (we're staying at the Anaheim Hilton for $75.)

The current one expires on March 31st. We had a large room at a great price, plus EMH.
Enjoy your trip to the World!