First thing that can go wrong is that actual servants show up and start asking what is up. We could use Honami, but I would hate to implicate her if we absolutely don't have to. We could do something like henge into Joutaro and tell the servants not to get close to the suite for awhile.
Cleaning happens on schedule. We get it from H and do this in the time window when normal employees are busy elsewhere. Maybe generate a mess specifically for us to clean, so we have an excuse of doing this outside of standard time.
Next problem is that we need to pass a Deception check against the person coming to the door. Even a competent civilian can pierce Hazou's Deception and Nobby has even less dice (we can raise it from 8 to 10), not to mention if the person coming to the door is a Deception heavy chuunin or up.
Not much we can do about that beyond preparing a fast exit strategy. Alternatively we could just have the normal servants muck up with water to create a diversion, but then we probably won't be able to get a read on their chakra levels.
Get Hazou to play the main role, with Nobby as support. Floor cleaning is not traumatic enough to trigger TYS malus, so 12 deception should be sufficient. Hell, our obvious practice at cleaning might even get us a circumstance bonus! Surely those hours spend scrubbing floors in the Academy have to pay off.
If they get suspicious and demand to see the manager, we could bring in Honami to apologize and assure them 'these particular servicemen' won't be bothering them again.
The next problem is breaking and entering stealthily. Mari should be able to spot the traps, but I'm not sure if she has any skills to undo them without triggering them with clones or Zephyr. Also, how are they going to deal with a window that is most certainly locked? Zephyr's Reach will probably help with simple locking mechanism, but if there's anything more elaborate there (Mechanism or Seals) they are boned.
Since the break in happens through civilian side, I don't think it will be so heavily trapped Mari can't deal. I doubt they installed their own locks in windows, so we're dealing with standard resort equipment.
We should practice a break in on one of other similar suites, tonight, if Mari thinks she needs it.
That leaves us seals. Honestly, I don't think seal masters happen to wander outside villages so often that seals are likely to be used.
We could bring in Kagome as part of sneaky group, just for the break in part? His stealth is good, though dogs may be a problem. He's sure to notice any suspicious decorations on/close to windows.
The stealth part is also an issue. I'm not sure if we get to do this when there's no light but in any case if Mari and Keiko are fiddling with the window in full view of the patrols and ninjas. Not sure how to help with this. Another distraction or are we just going to trust in our superior dice?
That mess we make on purpose? Do it in the evening to make sneaking easier, though J has to be away. If he goes for a late soak, good. We will know, since we should be keeping an eye on him anyway. If he doesn't.. in stealth we trust. If our sneakier members can't get past genin, we're doing the whole ninja thing wrong.
Maybe there's a tree to hide in nearby, and do the ZR from there? Resort is the kind of place where you'd expect to see a lot of greenery.
Besides, patrols aren't stationary. We figure out the best time window, and go then.
Then there's the miscellaneous problems. What if there are more than 3 people in the party? Smuggling more in would be a cake for a ninja and an excellent backup idea against pretty much any hostile elements.
Anyway, we are going to need good exit strategies when things inevitably go wrong.
Any other problems that need to be solved before we can write a plan based on this?
Not sure how there would be extra people in the party (did they get sneaked in in luggage?) but just looking in the window to see how many people are in the room should be enough to decide if breaking in is feasible or not.
If there's someone unaccounted for waiting inside we abort, and pat ourselves on the back for procuring more info.
(E: actually, leave that to Mari's discretion. Maybe plan "hit them with genjutsu while Kei goes through their things" can still work, Hazou and Noburi just have to distract two people rather than one person.)
Communication for two parties might be an issue. I'm thinking, Hazou and Noburi start on floor washing first, Mari and Kei hide in the trees or on the roof or whatever. Akane loiters nearby. When Mari decides to strike she sends Akane a message w/that wind talk jutsu, Akane quickly comes to Hazou and coughs loudly in our corridor or something. Commence watery distraction.
For exit strategy, how about drop everything and run? We have nothing to pick up. We have routes secured. Maybe split in two groups, one goes with Mari one with Kagome. Meet at predetermined point. Plan from there.
I want to make a plan out of this, but mobile bound again. Will hopefully make it to PC tomorrow, but.. well. Either way, hope to see more feedback.
E: as prep work, get Mari to take a closer look at the place this night, when it's dark. Dogs and patrol are not a problem even with her rolls, so she should find a suitable way to sneak into the suite, what cover there is nearby, that sort of thing. Examine the window for traps/seals (without doing anything about them!) and yeah, break in one of those other suites as practice. It'll be good for her.