As a Seattle resident, I call tell you that buses are everywhere here. The city has comprehensive public transit, and a huge portion of the population is dependent on buses to get to and from work.
You can avoid the "people wanting to get on board" problem if you put up a "TO TERMINAL" sign or similar indicator that the bus is out of service and returning to base. This could raise suspicion if you're headed
away from the base indicated, but only among those who know where the base is and actually stop to think about bus movements beyond "Is that my bus? No? Well, who gives a frag, then?" (i.e. police and metro employees)
Being parked in a place that metro buses don't usually park or heading down a street that metro doesn't use as a transit route is a little more likely to draw attention. In other words, stick to streets that buses normally use as much as possible during your travels. That way you're just another bus passing by instead of "WTF is that bus doing here?"
Tour buses and the like don't follow normal routes, so you may want to switch disguises soon after getting off the main bus routes, but the also draw far more attention. You won't be lost in the crowd in a tour bus: you'll stick out like a sore thumb.
Also, you should be aware that in the present day, metro buses have realtime tracking, and the data is used to calculate estimated arrival times that constantly update. This is available online or on mobile devices through websites like
OneBusAway. If they catch on to the fact that you're impersonating a metro bus, some enterprising cop might have the realtime tracking data put up as an AR overlay and look for the bus that doesn't exist on Metro's database.
Now, if you can rig your bus so a smaller vehicle can fit inside it, then drive your initial getaway vehicle into the bus when you're out of sight of pursuit, then have the bus play metro and non-chalantly roll away while your pursuers are searching for a subcompact...
that ought to throw them off the scent quite effectively.
