I love my pet rat. I don't understand people complaining about rets being smelly animals -- I clean Link's cage about once every five days or so (which is pretty infrequent IMO), and it only starts to smell a bit around the fifth day -- and even then, it's not that bad unless you go right up to the cage and sniff hard.
Some things you should know about them:
- They are very social creatures, so if possible, get more than one. If you absolutely can only get one (maybe due to small cage space or something like that), make sure you interact with it as much as possible -- at least a half hour a day.
- Their cages should be placed in a moderate-to-high traffic area, as they enjoy watching people go about their daily activities.
- If you handle them enough, they'll become quite tame and will enjoy riding around on your shoulder while you do whatever you'd normally do.
- Tumors: the rate of mammary tumors in female rats is between 75-90%, so it's a good bet that your rat will eventually get one (I'd recommend a female, BTW, as males are generally more prone to biting and smell a bit more). The tumors will swell up rapidly and look very large, but they generally don't cause the rat any pain. Rats only have to be euthanized for a tumor if a) the tumor is preventing them from walking, eating, or any other normal activities, or b) if the tumor gets infected and has sepsis, which causes the rat a great deal of pain.
- An average rat will live around two years.
Rats are a far better pet than any other rodent, IMO, because they are so intelligent. It's not uncommon for a rat to invent "games" to play with you -- for example, my rat enjoys being taken out, put into a blanket, and peeking out at me from random points in the blanket. The object of this is to see if I can guess where she'll peek out next. It's clear that it's a conscious decision on the rat's part that it's a game, too, because if I walk away she'll come out of the blanket outright and look for me until I come back.
EDIT: I forgot to address your question about going on trips: if your rat has a companion, they should be fine for at least a week while you're away, provided they have enough food and their cage is well-ventilated (which it should be anyway). If you're away for much longer than that, the cage might start to get an over-abundance of ammonia fumes from their urine, which could give them respiratory problems. If your rat is by itself, I would not recommend leaving it for more than a day or two.
Also, an important note about bedding: DO NOT BUY pine or cedar shavings -- these shavings give many rats respiratory problems.
