I originally ran a Comet CA-2X4 type antenna as this covers not only the 2M and 70cm bands but also does a half decent job of covering some out of band applications as its a wider Q than most dual band antennas. From memory there is a sub-model that specifically has extra coverage for MARS/CAP type applications - might be the -ER model? I eventually swapped it out for a small diplexer and two separate antennas - a half wave end fed VHF and a UHF tuned higher in the band as the Comet performance dropped off above 460MHz and I wasn't using 70cm much. In the US your FRS and similar type applications are much closer to 70cm so the Comet is probably more than enough for you. It is a slightly large antenna though and not super resistant to passing brush!
It probably goes without saying but I will say it anyway: in radio, the performance of the antenna, the quality of the coax and connectors and the proper placement of the mount are all WAAAAY more important than any other single factor. Don't cut corners on that stuff and make sure your connectors are properly sealed and strain relief installed etc and you will have a much happier time!