A bit late to the party but just wanted to share my experiences.
I've just finished university, but I've been dating a soldier for nearly 2 years now. He is stationed a good 3 hours away from where I live, but has tried to come up every weekend that he can. Obviously, due to the occasional weekend duty, he doesn't always make it, but I see him more often than not.
By the time he reaches my place on a Friday after work, it's usually quite late evening - he can't just leave the second work ends, as he needs to make sure he grabs everything he needs and has completed everything he has to do. If your partner can drive, that makes things a lot easier than needing to take public transport every weekend.
I find that weekends feel very short - he arrives Friday evening, we spend Saturday together, and then he usually leaves Sunday afternoon. If we had kids, I would probably worry about whether or not they spent enough time together each weekend.
As a girlfriend, I can confirm that marrying before deployment would be a good decision if possible. My boyfriend does not have me down as his next of kin currently, and so his predeployment information booklet and important numbers went to his mother, who I am lucky enough to get on well with. Wives are usually kept relatively well updated with what's going on in terms of deployment, but girlfriends (and apparently mothers!) are not. Additionally, if something happens to you, being married means a greater chance of him being put on the next flight home, from what I've heard (although as you have kids together, that may make your situation regarding this slightly different- there's a lot of useful information online if you search for it regarding family and girlfriend rights during deployment).
Hope that helps!