Hi,
Our son Joshua was diagnosed autistic in 2001.
He has been to Florida I think 6 times now and will be doing so again in April 2009.
What you say is very common with some kinds of autism, it is difficult to be exact because there are many different kinds and children react differently to certain situations.
Joshua has always displayed the issues you are concerned about, and they are related to being in unfamiliar surroundings and a lack of patience.
He doesn't like eating out, going in shops, supermarkets and general areas that he isn't faced with regularly..although strangely is much happier in the malls in Florida than he is at the likes of The Trafford Centre in the UK.
It also isn't nice when he gets upset, especially in public...unfortunatley this is just part of the condition and sometimes you have to block out what other people think - he does get stared at on occasions.
One of the other things to bear in mind and certainly in our case is Josh looks like any other child (he is a handsome chap!) so it will not necessarily be apparent to others that he has disabilities.
Your close friends - firstly they shouldn't think twice about going, Joshua on the whole reacts very positively to a Florida holiday. The long flight and the high temperatures are the main concerns for us.
Queues for rides - Joshua has definitely shown improvement over the years and more patience, to be honest we enourage him to queue providing the wait time is less than 10 minutes.
At Guest Services get a GAC card, and use 'if you have to' - these can help your friends beat the long queue's and also make CMs aware of the situation.
I would however, not avoid the possible stress related areas - after all the child will never get used to a queue if they never 'have to queue', so it could be of long term benefit if they try the child - signs of improvement over time are a distinct possibility.
If it just isn't reasonable then use the GAC card. Using the normal queue especially when other children may be in line too will help the child feel just like any other child, and also help the parents feel they are just doing what everyone else does...this may sound a bit odd but I can assure you it is a nice 'buzz' knowing that you are waiting for a ride like everyone else is.
Most families with autistic children don't want to make a fuss, they want to do the same things everyone else does..so I would keep the GAC 'in reserve'.
They may also find getting to the parks early will mean it's quieter, which is a definite help, at Magic Kingdom for example you could do all the rides at Fantasyland first thing with limited queuing times - again this can help build the child's confidence.
I cannot stress enough though how it's down to a lack of familiarity, we rarely eat out at home - so can hardly expect Josh to on holiday.
Will the child be able to walk long distances? Josh cannot - hence we have a child's wheelchair that we use just for touring the parks, for some reason linked to his autism he cannot walk for too long, although round a mall etc he is fine.
I think the best advice is to go with a positive and open approach, they will have a great time. To be honest it is likely the child may get stressed on occasions - it would be wrong of me to say otherwise - however, they will deal with this as it occurs, all parents with autism have a few key factors in their favour...patience being one of them.
Most of our recent stays have been in a villa, usually close to the Formosa Gardens area - if I for example was to drive past the exit and carry on to the supermarket Josh would almost certainly get upset, because it deviates from the normal routine....10 minutes later we are back on route to the villa and he is happy again...just an example of situations you have to deal with.
I would tell them to be wary of rides with pre-shows, this stretches the patience factor a bit too far - with the GAC card they can skip pre-shows if they choose to (this is important to remember).
Fact is there are some rides Josh will never be able to go on, the shorter the ride the better, anything that involves a long pre-show and then a long attraction - an example would be Shrek at Universal Studios, it's a good 30 minutes long and a definite no for us.
The longer the time of the attraction the more likely the child may get upset. So it's worth bearing in mind.
If they can do some research as to what rides they think they can go on and what maybe to avoid that would be a good thing.
Tell them not to worry, not to avoid a queue where the wait time is short as practice is a good thing, don't avoid the possible problems - confront them, the worst that can happen is a little bit of upset for a few minutes....be aware also that many do not understand autism, sometimes as parents you have to block out what other people think or are looking at.
I have lost count of the number of times people have stared at us over the years, whether in Florida or not - unfortunatley that's something we have to deal with....and they will be fine.
They will have a great time, tell them to go for it - if you need me, send me a pm.
he is usually on the boards so you will get some info 
