As was mentioned, if you're looking for vehicle-to-vehicle communications while traveling with a group then find out what most of the group uses. I find that most clubs/groups use GMRS these days and with more GMRS repeaters popping up there is more widespread use for general comms (Dur, the G in GMRS. :) ). The cost of entry is relatively low for a service and gear that has the potential to reach decent distances if properly set up. No exams, etc. to deal with.
Amateur/ham radio can be as simple or advanced as you want. Exam and transmitting requirements aside, a simple 2m/70cm dual-band radio programmed with local repeaters or repeaters where you'll be traveling will provide you with similar capabilities as GMRS, the 2m band will have better reach than 70cm (GMRS operates near the 70cm band) and with an APRS-capable radio and an iGate or digipeater within range you'll be able to send and receive SMS messages when you don't have cell signal. I've done this with my Yaesu FTM-400XDR a number of times.
If you want to play around with more ham bands then something like the Icom IC-7100 is a great mobile option.
I haven't used CB in years. I wouldn't give it a second thought unless your group uses CB for vehicle-to-vehicle communications during group events.
So, think about your primary use(s) for the radio(s) and go from there. For me, getting into ham was mainly for comms during solo travel and "SHTF." GMRS is secondary and only used when traveling with a group since that is the easiest for everyone. Nothing wrong with having multiple radios and covering your bases, either. There are a lot of options and abilities/functions available out there, we haven't even touched on digital radio (DMR, D-STAR, System Fusion/Wires-X, NXDN, etc) either which is something else to think about when it comes to ham/amateur radio. Making contact with a local amateur radio club would be a great resource to help you figure out what would suit your needs the best.
Also, check out
RepeaterBook.com: Quick Search for Amateur Radio Repeaters and
RepeaterBook.com: Quick Search for GMRS Repeaters to get an idea of what repeaters are available in your area or where you plan to travel. While not 100% accurate/up-to-date it will give you an idea of what repeater options are available and what modes they support.
Good luck!