I would imagine it depends on your setup. Do you have mostly everything automated? Timers,etc? Is there a CA reactor or anything that doses that you are concerned about while away? If its simply feeding, you can buy an auto feeder to take care of that for one week, they are like 30-40 bucks or so I think.
I went on a 5 day snowboarding trip and was worried about leaving my 75. All the equipment I bought finally was put to the test for the first time. Reefkeeper to control temp. And light, Filled up the ATO enough so that I know there would be enough and then some for my trip and double checked all my equipment before I left. As for food, there is enough copopods and mysis in my tank for the fish to eat while I am gone so not too worried about them going hungry. Lastly I asked my sister to check on my tank every night to make sure everything was ok. I lucked out this time but vacation disasters happens a lot so good luck!
Like Jay said, don't make any changes for a while before you leave. You want the system to be STABLE, not perfect.
I wouldn't worry that much about feeding, but if you do have someone feed the tank make sure they're not going to over feed. Auto feeders are a bad idea IMO.
Take your magfloat cleaner out of your tank and hide it! We've aquired a few tank scratches from unknowing tank-sitters who were just trying to be helpful and get the algae off the glass. they were unaware of the sand in the scrubber.
I completely agree - in the 8 years of running our tank, I can say that things are most likely to go wrong in the week after something is messed with, or after a couple of months of not doing anything. When leaving for vacation you want to be in that sweet spot of having everything "tuned up" two or more weeks prior to leaving. I have had good experience with auto-feeders - while they probably didn't need it for a week or so absence, the fish do like easy food on a regular basis. I've read bad stories of having others take care of the tank while you are away - forgetting to restart pumps after feeding, dumping something wrong in the tank, etc. I've always left with no scheduled care from others - but it is a good idea to have someone who can check on it and help if something goes wrong. Also, try and design the system so that if any one thing fails it won't kill the system. Use multiple heaters, circulation pumps, etc. Ask yourself what would happen if a piece of equipment were to fail - how long until things would get "bad", and how "bad" would it be? As much as is reasonable, what can be done to help with that? These things help even just for leaving for work for the day, but are more important if you are leaving for a week. The one thing I really haven't been able to deal with is electricity. Even though I have a portable generator, it is way beyond what I'd expect someone else could do to hook it up and keep it gassed and running if electricity were out for an extended period while away on vacation (still feeling the pain of two years ago). I also have the tank temperature, and sometimes, live pictures available on the web that I can check from my phone, and so I could find out if something were wrong in order to call someone for help.