The problem you will run into is most of the multi band radios (except those with built in APRS modems) have a limitation that makes using APRS simultaneously with voice problematic. Think of it this way: the 8900 is a quad band radio, but a dual channel radio, meaning you can tune slot A to one frequency and slot B to a different frequency. You can then listen to A and B at the same time. When some one on the slot B frequency calls, you switch to slot B and transmit your reply. The TNC may modulate APRS and send it in as audio through the mic input or in a serial input on the device, but on pretty much every unit I've seen, it transmits on the frequency of the currently selected slot. Since most APRS beaconing is automatic, you won't know exactly when it will beacon next. This means that if you want to use automatic beaconing on one frequency, and voice in parallel on another frequency, these units won't work unless you are prepared to switch from the APRS channel immediately before you transmit on voice, and switch back after you complete every transmission.
Generally for flexibility you are better either settling for 2/70 and getting the Kenwood or Yaesu radios with APRS built in, or splitting APRS into a seperate self contain unit. This could be done many way, but one option would be to get an all band such as the Icom 7000 or Yaeso 857 to use as your voice rig (160m-70cm). The get a handheld, and interface with android tablet using APRSDroid.
