I've been blissfully married for 3 years now. We don't have any kids yet, but we are getting plenty of practice. We plan to be pregnant by the end of this year.
That is my history, thought I would let you know before I comment on this thread.
There are some key things to marriage. Both parties have to be ready for commitment. Personally I think that if you are under 25, you are too young. You need to each have a life established, before you marry. And when you reach a time when you think you are ready for marriage, live together first. You may have dated someone for years, but you will learn much more about them when you live with them. If you can't live with them, you can't marry them.
Finances are also a big factor. You need to be completely upfront with you partner before you marry about what financial situation you are in. For example, my sister-in-law got married only to find that her husband had $20,000+ in credit card debt. You need to be with someone who is financially similar to you. For example, save your money and marry someone who will also save money. Financial factors/debt break up a lot a couples.
Sex is another very important factor. Another thing that will break up couples. Giggle all you want, but you have to be able to talk about sex with you partner (25+ yrs old so you have some maturity on your side) You have to be with a parnter that is sexually compatible with you. Example, you have the same sex drive, you like the same things. A health sex life will definately keep a marriage healthy. A lot of people say that your sex life dies when you get married (job and kids get in the way) but I think it is important not to let it die. Make an effort. Granted, my wife and I were friskier when we were courting, but we still make the time and I think we are more active than the average married couple.
Kids. Do both of you have the same family plan? This is huge. I think this can also spoil a lot of couples. I would also suggest that any newly married couples wait a little while before having kids. Establish a family dynamic of two before adding. Plus, there are things you should get out of your system before having kids, traveling and such, that is harder to do with kids.
Dante_Alucard also makes a very good point. Things in common are great, but you can also do your own thing. And the whole surfing while one plays a game, you just described the average night at my house.
Compromise. Always be willing to compromise. And this is more of a comment of finding someone who you are really compatible with. If you find yourself fighting all the time, you might need to take a good look and find out if this is someone you need to marry. Also, don't go into a marriage thinking you will change someone. You should love them as they are, no exception. You really need to marry your best friend. Your best friend that wants to have sex with you.
The expensive wedding is really only as expensive as you want it to be. A wedding should never financially cripple you. There are inexpensive ways to do things. My wedding and the most recent one I have been to were on tighter budgets and they were absolutly great. A problem I have seen is that the parents can get over-involved and invite too many poeple. You just have to put your food down (even if they are giving you money for the wedding) and tell them that this is your event, not theirs. Get your friends to help, you family. Hell that is what it is all about. Friends and family coming together to celebrate you love and your commitment. And you are there to publicly declare you love and commitment. If you are not willing to say to the world, "I am ready to spend my life with this person", don't do it. That is why there are so many devorces now. I don't think people are ready.
Wedding presents are fraking awesome. We got an entirely new kitchen out of our wedding. It rocked.
To sum up this lengthy thread. If you are unsure about getting married, don't do it. There are so many people getting devorced now and I think it is because they are too young and just not ready. If your are looking for financial benifits to being married vs a live in girl/boyfriend, then you are missing the point. A marriage is a life long commitment (too many people forget that) of love. I don't care what comes our way, but my wife and I are in it for the long haul. Whatever problems may come up we will handle them, together. There are some good examples of marriage out there, so don't let the majority of unprepared people get you down. Marriage is work, and you have to keep working at it. But if you do, you will find that it can be the most wonderful thing in the world and will make you life all the better.