hi!
Not sure if you already have... but I would say the best way to decide is to have a really good look round the shows.
I chose st tropez Air because I thought the name would sell itself, and it has to some extent, but I think it's prob a bit expensive, and another systm would have been better in terms of application, practicality, length of time taken to apply etc.
I too, am hopefully opening a salon shortly, and def can't afford an integrated booth system - instead I'll use my St Tropez portable system, in a treatment room set-up with a curtained/tiled area that can be easily cleaned.
Ventilation is essential to draw out the vapours-they can be quite overpowering! An electrician will be able to calculate what vent is needed - make sure you tell them that it will be drawing out a particles of a coloured liquid (in my last salon the system leaked and tan solution dripped through the ceiling!!)
When I went to ExCel, I really liked the look of the Fantasy Tan portable system-can't remeber the details - but it has a reputation already from the salon, and looks easy to use.
THings to check are £cost per application?, £price/treatment? (St tropez strongly recommends all it's retailers sell the treatment for a similar price), Retail Opp's?, How long it takes for one treatment?, how quickly the tan dries?, advertisig done by the company to the end user (i.e. in mag's etc-any celeb users?), guarantee/warranty periods?
Can't think of any more at the mo!
I would also DEFINITELY try out each system before you decide! I didn't and wish I had - this way you can be more confident when selling your chosen system above others!
Training... St Tropez gave me a day 'in-salon' training, and 1 day at head quarters in nottingham.
From what I have seen Su-do offer one of the most formal training sytems - yu can complete NVQ level (i think-corretc me if i'm wrong) in airbrush tanning/make-up/hair art design/fantasy body art/and something else i think??
I've used the St Tropex Air system in salon and mobile since around April - so if you have any other Q's I'll do my best to help!
HTH... xx