Some other thing to condsider:
1) However big your staff is, let's say 20 for example, that's 20 different individuals, personalities, problems, opinions, gripes, etc. that you have to deal with. No matter how team-oriented your staff may be, there are still 20 heads that you have to try to get into to mentor, anticipate, lead, motivate, etc.
2) You are responsible for the actions/mistakes of your staff. Oh how I long for the days when all I had to worry about was my story, my gear, my news car, my cell, etc. Right now if someone on the staff misses slot, a piece of their equipment malfunctions, or any number of things then the ND comes directly to me and I've got to have answers whether I was on duty or not.
3) The days of slacking off occasionally or phoning it in every blue moon are over. All eyes are on YOU. If the photogs see you dragging ass then who are to later jump on them for doing the same? If the reporters see you dragging ass, then they may hang that on your staff as well. Next thing you know, you've got the ND is all over you about why the reporters complain about the photog staff. This can apply to vibe that you give off that others around you may pick up on (lazy, whinner, slow, and the list can go on). I learned this the HARD way...fortunately though, I learned it early.
4) Being a manager can put you in certain positions that you may not like. You may have to enforce or help impliment policies created by your supervisors that you may not like or agree with. You may be privvy to info about happenings or fellow employees that you want the burden to know. A couple of years ago, someone leaked info out of a meeting that totally made things tense in between two factions in the newsroom. I wasn't the one that let the cat out of the bag (there were six other people in the meeting, one of which was shagging the "leader" of one of the cliques) but since I was new in the position and was pulled into a meeting that I normally wouldn't be included in, the ND assumed it was me. To this day, I think he still holds it against me. Also, imagine working alongside a reporter that's excited about the new house she has just closed on and you know that the station is not planning on renewing her contract when it comes around. Stuff like that can eat you up inside.
5) If you are a shooting chief, then you will never get it all done. Sometimes it seems like I have more homework now than I did when I was in college. My wife was totally pissed off when I had to bring paperwork with me on our vacation to Hawaii last year. Couldn't help it but had to be done.
6) Money and title don't always equal happiness. It's nice having money leftover after paying bills and having "Chief Photojounalst" on my business card, sometimes I wonder if it's truly worth all the BS.
These are just a FEW of the things I wish I knew before I stepped into this positon.