Heres the list of what my initial thoughts after playing for a bit. Have a look through and see if you feel they are right for your game:
-make the room creation a select box. You click create room, click 1, draw a box which highlights the squares (and anything on them like walls/furniture). When you add furniture into this now flagged region it is automatically added to the room contents. You could also add modifier keys like ALT+LMB to add to the room and CTRL+LMB to remove, that way you could make rooms of odd shapes if you wished. (After some thought this idea reminds me of prison architect a bit).
-In the options add a "pawn reset" option which would reset all pathing and teleport all pawns to the starting spawn area. Ultimate bug fixer right there. (I noticed a few times workers or cleaners getting stuck on walls or trying to path through them. I even had cleaners stuck on spawn.
-unlockables:
-4, 6, 8 seater tables.
-Larger build area (starting build area needs to be reduced in size and unlocked as you increase prestige).
-Clone room tool so you can copy/paste whole rooms.
-Add icons to the food/cleaner/drinks storage zones and boxes so you can easily see what needs ordered and which squares are assigned to what.
-Mouse over tooltip for the resturant bar to see X/6 meals available.
-Change staff wages to /day rather than /h (I'm guessing /h is per hour but is actually charged at per day). A summary of your staff costs added somewhere around your cash total (Maybe in red brackets after your total).
-A progress bar under your cash to check on your progress towards your prestige level
-A notification area (top right of screen maybe). for things like "A guest is unhappy due to (REASON)", "A guest left due to (REASON)", "You are low on drinks, X minifridges need restocked", "You are low on cleaning products, X cleaners shelves need restocked", You are low of food, X fridges need restocked"
-Guests requiring specific needs (this may already be in the game, idk)
-Couples requiring double beds (add double beds). Groups requiring rooms with 2 or 3 single beds.
-Change the music hard-cut when you change between manage and build modes (make it fade out/in).
-Tables require cleaning, some guests use a nearby bin so tables require less cleaning. Bins require emptying. Cleanliness has an impact on guest happiness.
-Shower, sink and toilet requiring cleaning after a few uses. Maybe somewhere between 3-10?
-Additional decorative items like more flooring, wallpaper, curtains, table options (tablecloths or table designs), themed items under different pages in decorations (I see you already have a few) Xmas/Halloween/Valentines/Easter/etc...
-Guest overview (like staff one) by clicking guest number icon. Show the same as mouse over but for all guests in tableform.
-Mouse control camera
-Staff only doors
-Price beside supplies order button so you know what each one costs (since they have different prices).
-Pause, Play and X2 Speed buttons.
-Reword "cleaner's things" to "cleaning" in supplies order menu, "cleaning supplies box" when mousing over box and "cleaning supplies" when mousing over cleaners shelf. If all of these places reference the item itself just rename it to "cleaning supplies"
-Maybe add the ability to build additional floors and add stairs/elevators. Add a + and - on the side with the floor number and add teh ability to click notifications (see above) and "zoom to" the problem. (I added this last as its probably somethign to add MUCH later, once everythign else is implemented, maybe add this as an unlock?)
Anyway, just a few thoughts and suggestions (some already mentioned in previous posts by others). Great start though.