Going on an interview, asking for an extra flight?

[Yobz]

My roommate is going to be flying out on an interview (company pays for flight/room/meals/rental/etc) and wants his significant other to check out the area to make sure she is ok to move there (they would both be moving there). He asked me for advice and I turn to OOT knowledge because I have no clue what the answer is:

Is it alright for him to ask the company to also pay for his so's flight so she can see the area in which they will potentially be living?

On a random side note, we got into an argument. He's planning on wearing khakis and a button up to the interview (tech company) while I say a suit is the way to go...