Put the sign on first
A big sign is what makes a block building read as a hotel. Pixel letters are easy: make each letter 3 blocks wide and 5 tall with a 1 block gap. Put them on a dark board so they pop, and add lanterns at the ends so the sign glows at night.
Use one floor height
Pick a floor height and keep it. Four blocks from floor to floor (three blocks of air and one slab) fits a player with room to spare. Repeating that height makes tall hotels easy to plan and keeps all the windows lined up.
Windows in rows make it look like rooms
Glass panes in even rows, one window per room, tell your eyes this is a hotel. Leave a plain wall column between windows. Blue stained glass looks fancy and hides the inside, while clear glass lets you see the beds.
Make a lobby that is taller than the rooms
Remove a patch of the second floor above the entrance so the lobby is two floors tall. Add a desk made from planks or quartz, a few plants and lanterns hanging from the ceiling. It makes the front feel grand.
Light every floor so nothing spawns inside
Hang a lantern or two on each floor, and put lamp posts along the path and around the pool. Monsters spawn in dark spots, and hotels have lots of dark corners. Lanterns under a ceiling are the easiest fix.
Add the little things guests use
A pool with a quartz edge, loungers made from white wool, umbrellas made from fences and a wool cone, a fountain and flower beds all make a hotel feel lived in. A drive-up canopy over the door with pillars is a quick way to look expensive.