We used a cab this past weekend (both were minivans, so would have been OK with 3 kids). With tips/tolls, $40 each way to HRH.
I normally book a car service to disney (cheaper than a cab), but I will probably do cab service from now on to/from Universal, as they are more expensive to/from Universal and I have had problems with several car services (FL and Tiffany have both shown up at least 20 minutes late in the recent past to take me to the airport for departing flights).
Have a great time!