I had a great time wheeling around Monterey near Cannery Row and the aquarium. If you have wheels and you have not been to Monterey before, perhaps this entry will allow you to feel a bit more prepared.
If you stay in a hotel on Cannery Row, you're in good stead to navigate that strip of shops and restaurants. The sidewalks vary between generously wide and just wide enough, but the paving is fairly good. Expect a few bumps and cracks for history's sake.
If you choose to stay a few blocks inland, you need to be prepared: it's definitely downhill to Cannery Row and then uphill to your accommodations. David Street is too steep for my scooter, but we had good luck with taking the more gradual Irving Street whenever we headed away (southwest-ish) from Cannery Row.
The Monterey Bay Aquarium has very good accessibility, with one notable exception: the captive sea otter exhibit can only be reached by stairs. If I may be bold, please don't let this inequity ruin your time--I was able to wheel into/over/through every other exhibit and the sea otter exhibit in Monterey is not outstanding...the one at the Aquarium of the Pacific in Long Beach is much finer, sea-otter-wise. Also, you may wheel outside to the observation deck at Monterey's aquarium and watch the ocean for non-captive otters, which do turn up pretty regularly.
Access into the shopping enclaves on Cannery Row is adequate. I found myself colliding with the wares in some of the stores...in truth, the aisles could be a bit wider in about half the stores we checked out, but I didn't break anything or knock anything over, and the proprietors were very friendly and quick to move obstacles out of my way. I suspect the high cost of rent along Cannery Row makes piling as much merchandise as possible into each store a matter of business survival.
The motorists in Monterey were really very pleasant as I wound my way through the streets at 4.6 miles an hour. I hope that if you decide to investigate Monterey on wheels that your time is as pleasant as mine was.