I'll happily second the Larsen line. I've been using and installing those for years and have never had an issue with them.
For the mount, look at the NMO mounts. Larsen NMOK would be the basic one, although I've been using the NMO mounts with the dual shield cable as it has a bit less cable loss. You don't need the NMO-HF mounts for VHF, although it wouldn't hurt. Those are designed for really high frequency stuff. The NMO mounts are about as standard as you can get, and once you have the mount installed, you have a wide selection of antennas for many manufacturers that will fit that standard mount. Real permanent installation is preferred and while it does involve drilling a hole, I've never had one leak. You can usually pay a shop to do it for you if you don't have the right tools, or are squeamish about taking a hole saw to the roof of your truck.
For the actual antenna, you have a number of choices. Quarter wave is my favorite, especially for a truck roof since it will be the smallest useable antenna. NMOQ would be the Larsen part number, although there are several versions, including chrome and black to fit your preferences. If your truck is tall and you are concerned about low hanging trees or parking garages, then look at the quarter wave antennas that have a spring at the base.
Since your area is pretty flat, you would also want to look at the 5/8's wave antennas. At VHF frequencies, it's going to be about 4 feet long, but gives you a bit more gain. I've never actually seen a big improvement in range with these, but some claim they do. On a pickup they tend to find tree branches and low parking garages, however. They tend to be quite flexible, and that can help, but at freeway speeds they also bend over quite a ways that I think reduces their effectiveness while driving.
One thing I suggest to people is to look at what the local public safety agencies are using. If the locals are on VHF, see what kind of antennas they are using. That will give you an idea of what works in your specific area.
Installing these on your own is relatively easy, but does require the right tools. If you plan on doing more than one, I'd suggest spending the $20 or so to buy the proper hole saw. It makes the job easier and is designed to not go too deep. If this is a one off install, then check with a local radio shop and find out what they charge to drill the hole, install the mount, and tune the antenna for you. It may cost a bit, but they'll likely do a really good job.
Other vendors than Larsen:
Maxrad,
Laird
etc. They are all pretty much the same and any of those brands would be just fine. I'm sure someone else will pipe in with their own recommendations.