While I do not have exp with those particular companies just call and ask for references.
We took a limo from Ft. Lauderdale into Miami a couple of years ago and we never called anyone for references other than google and everything worked out wonderfully. Best money ever spent. I am just not into the cattle calling of tours or bus rides. Just do some research online and I am sure you will find all you need. Check out the BBB in the Houston area, also they are a great resource.