I look for big accommodation and lots of experience.
With hutches, look for ones that give at least 12sft (the equivalent of a 6x2 hutch), as anything smaller says to me that they are either not aware or do not care about the RWAF guidlines. Even if they have one decent hutch, if they have many other small ones that they suggest your rabbit would be fine in, that indicates a lack of knowledge/research which may extend to other things like diet and health too. I'm quite fussy with boarding, but its because I want to be able to trust that the person they are with will a) notice an emergency quickly and b) know the right course of action and c) ensure my rabbits' time there is stress free with as much space as possible.
Also have a look at the runs available, not just size but as others have said what they are on due to cross contamination. Ask whether your rabbit gets its own run for only its use whilst it stays, or has to share with other rabbits. If sharing, is it disinfected between occupants? How long will your rabbit get in the run each day? 'It depends on how many other rabbits are staying' is not really an acceptable answer, what if there are loads of other rabbits there and yours only gets a couple of hours in the run? You want a guarenteed 'at least' time they will be in it.
I prefer aviary-type setups, as the rabbit will have sole use of its run all day, whilst being able to get back to its house area when it wants, and the size of these setups is usually very good, especially as the rabbit has permenant access to all of it. The same goes for hutches with attached runs.
And test them, ask them what will happen if your rabbit has such and such happen (isnt interested in dinner for instance). Ask lots of questions, and you will be able to guage how experienced they are and how up to date their knowledge is.
Ask about every detail - for instance, a place seemed fairly good to me until I picked up on the fact that if it was raining, the rabbits stayed in their hutches, alright that's not disastrous, although sheltered runs would be much better. Then the lady said they could run about indoors - great! When I enquired further I found that what she meant is that they could run about in the rabbit outhouse/room, where all the hutches were. They would take turns have free-run of the floor (not great as she had many at a time and so they wouldnt get long out) and from the pics of this place I could tell she meant they would be able to go right up to the other hutches. From the point of view of safety from injury, disease cross-contamination, and stress of interacting with rabbits unbonded to them, this was unacceptable and what seemed a very knowledgable place suddenly was revealed to be somewhere that did not know its stuff at all.