I saw there's Hyatt and Holiday Inn hotels in tact with the mall and the River Walk route.
The Grand Hyatt, La Quinta, and Marriott are all very close. The Grand Hyatt has it's own parking and right across the street there is a $10 flat rate all day parking. There is even a dedicated riverwalk passageway right from inside the hotel through Ruth's Chris Steakhouse.
Hyatt Regency, Marriott, Hilton, on East Houston street you have other choices. We stayed at the Hilton Garden Inn which is 3 blocks from RiverWalk and opposite 3 blocks to the Alamo. I wear a knee brace and use a Cane. I walked with my Husband.
Can't remember the name but there's a hotel off the Riverwalk. I wanna say right by where you hop on for boat tour.
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