I am a Gov't Engineer. So here's my take on things:
Pros:
1) I don't ever have stress over losing my job. In fact I've often wondered if I just stop coming into work how long it would take them to fire me. I can't be fired unless I steal or threaten the president.
2) My childcare is excellent. I also get a "mishap report" anytime something happens to my kid. I find this somewhat hilarious because it actually has the Gov't form number on it. Pro is that its a very consistent level of care, Con is that you can't expect people to problem solve or actually think.
3) Love my sick leave, I use it whenever, including Monday-itis
4) TSP is great, you get a 5% match and I think you're vested after 5 years (have to double check, its been awhile since I cared). You can also take loans if needed and pay yourself back at the going rate (currently 2.25%).
5) I'm not counting on the pension, but its not that bad. I would not consider this as a factor when choosing.
6) OT - make sure you actually get time and a half, lots of folks just get straight time. Additionally, most organizations have an OT budget and if they spend it you still can't work. So don't count on this, just consider it a possible perk
7) Per diem rocks, and I don't even travel that much.
CONS:
8) They may only match your salary, but you should ask for leave accrual. Note, YMMV, each agency sets its leave policies. Most feds I know get paid every two weeks earning 4 hrs/pp for <3 years experience, 6 hrs/pp for <15 and 8 hrs/pp for >15. Ask for leave accrual based on the time you've worked already.
9) Are you done your degree? There are many programs to help fund feds getting their Master's. Each agency is different, you'll have to ask specifically about tuition reimbursement programs.
10) Skilled workers always get paid less in the Gov. Unskilled workers tend to get paid more (strange, isn't it) if you count benefits. Also, be aware that you will not be getting a COLA unless Congress votes on it or bonus money if its not budgeted by your agency. The last few years we got no bonus money but did get "time off awards". The max bonus money in my office last year was about 0.8%, but again each agency is different. Before the economy tanked a 2-3% COLA from Congress was not unheard of (realize its not really a COLA, it is Congress voting to increase all the pay scales so technically it is a "raise"). The bonus money just depends on how much they've got in the pay pool.
11) I started on my MMM Journey because I could not stand my job's bureaucracy anymore. So make sure you have an exit strategy. 12 years is a long time, I am not sure you will make it if you have a low tolerance for bureaucracy. Additionally, if you stay more than 2-3 years you will get sucked in and never leave. Be aware.
12) Typically the closer you are to real work, the less likely you are to get furloughed. Last year was unique in that they furloughed everybody, regardless of funding. Which is kinda stupid because most people's budget is NOT appropriated (Congress voted on) funds and they were already budgeted for. The Gov't shutdown that occurred after the regular furlough did not affected the non-appropriated funds people. Most of the Gov't went to work as normal. Only the folks paid for by Congress's budget got to stay home. And while it sucks they didn't get a paycheck those weeks, they did get all of their money eventually (back-pay). So essentially they got a free vacation. My DH is appropriated funds and I am not. He stayed home and re-did our 2nd bath that we had been planning to do together over the weekend. So I got a slow week at work and he had to do manual labor!
13) Ask for leave accrual. Don't forget.
From a technical standpoint, it sucks to be a Gov't engineer because we tend to contract out all our really cool projects. But to me the other amenities are worth it. I have to remind myself not to be a complainy-pants because I have it really easy.
For the poster about the sick kid, if I had to take off for something that long it would also be unpaid. Maternity leave is unpaid. They have to LET you take leave based on FMLA (I think contractors do to), but they don't pay your for it. You can use your sick leave and annual leave, but after that you're on leave without pay. Isn't this pretty typical for America, though?