Ok, I'm no stranger to the faux-tan. The OTC creams work a bit, will take the "ghost" away, but you won't be "tan" by any stretch of the imagination.
If you go to a salon and have them airbrush you then you will be tan and it will look awesome. Yes, it will last 3 days, then gradually start to fade. they will tell you it lasts a week. That is a bunch off crap. It doesn't.
You can't get wet for at least 8 hours after spraying- so if it's raining outside forget about it.
If you go the day before your cruise you will be good until the day you get home....and no, it doesn't come off on your clothes at all.
You WILL feel sticky after the application. Best to wear loose-fitting clothes to the place, and there is a bronzer in the initial application, so that can rub off on your clothes. After you take your first shower though that washes off and then nothing will rub off after that.
It is not cheap, but if you feel that having color makes you more confident and happy then go for it. I know it really makes me less self-conscious. I do it sometimes before we go to Disney b/c I feel like my skin is so white I look blue sometimes. I love having a tan and wish I could just feel better about my natural white hue, but it's something I've never come to terms with.
good luck and have a great time!