Only people who know affiliate marketing will worry about the affiliate links. most of the general population has no clue. I have cloaked affiliate links and have not seen much difference. I think it was a game a few years back to sell some cloaking codes when they first came out.
As far as affiliates that are trustworthy, I would suggest you test, test, test!
That is the beauty of an affiliate site. you can change affiliate programs at will if they do not produce.
Banners, links, whatever. It is easy to change one 120 x 120 banner to a new one in a few mins. And a text link is even quicker to change ( i always prefer text links).
If you set the site up right, by the time you get the
SEO working for the travel industry, you will already have a decent idea of which ones produce.
By the way, I hope you are a good
SEO if you are targeting the travel industry. I would suggest that you work your
seo to local results over national.
Hope this helps.