I LOVE my firstwheels for the reasons you mentioned. They are they same width as a wheelchair so normal doorways are fine and I haven't had a checkout problem yet (use the wheelchair accessible ones if necessary). Also no problems getting around with it either - we took it to the show too!!! Trains can be a challenge but you just need to choose the correct side of the pole to enter through. Wouldn't try a bus though - too chicken!!

I get lots of questions from people too because of the versatility

ETA - if you do an internet search for purchasing you can get significant discounts. I got mine for half the RRP.