Our oldest has completed one year of college, and here's how things worked out for us:
We bought her a laptop for Christmas her senior year. That's an absolute necessity.
We spent a moderate amount getting her ready for college. We didn't do the she must have all new stuff for a dorm room thing, but we did buy her new bed stuff (mattress pad, sheets, comforter, pillows) and consumable supplies (toiletries, Tylenol, and other things that we keep around the house). Aside from a parka and snow boots, she didn't get many new clothes, she's using the same old backpack and calculator, and she already had things like a bedside lamp and an alarm clock that also charges her ipod. She received towels, a laundry basket, and some other dorm-needs from family as graduation presents. I think some people duplicate everything the kid has in at home so that when she comes home, she still "has everything", but we didn't do that.
We have saved since before she was conceived, and we saved with the assumption that our future children would earn no scholarships. In the event, she has about 50% of her total cost paid from two scholarships, so the big bills have actually been easier than anticipated. Also, she chose a school that includes textbook rental in its tuition, so that large bill didn't materialize.
We ended up spending more on move-in than anticipated -- that caught me off-guard. We ended up buying some expensive cables to hook up her printer, Command hooks, and a few other last-minute things that added up to more than I would've thought. We all drove up and spent the night, which meant a hotel and several meals. We also ended up renting a van because her stuff wouldn't fit in our small car. In May we rented a storage building rather than bring it all back home; our reasoning was that we won't have to rent a van again this fall, and the stuff hasn't been sitting around in the corners of my house all summer.
As for around the house in the months she was gone . . .
I can't say that our water or electric bills were any different. I mean, we continued to heat the whole house, and 3 people showering isn't all that different from 4 people showering. Cable TV, of course, has remained unchanged. Our car insurance doesn't care that she drives only occasionally when she's home.
Our grocery bill definitely went down while she was gone. Admittedly, she has some unique dietary requirements, and they do drive my grocery bill up; thus, our situation might not be entirely typical.
We've been eating out more frequently than we used to, perhaps in part because it seems cheaper now that there are only three of us. Of course, it kind of backfires on us sometimes: For example, we used to order two plates of Chinese take-out, which was plenty for the four of us . . . now one plate isn't enough, but two is too much.
Oddly enough, she was forced to buy a relatively large meal plan, and she wasn't using it all . . . so when we went up to visit, she bought us food from her meal plan. I'm glad she's able to buy a smaller plan as a sophomore.
Gas money doesn't seem to be different. First because our life is fairly well consolidated, and we don't go too far from home; second because we still have another child at home, and we're still running her around.
She comes home about once a month, but usually she catches a ride home with a friend; when she does this, we always give her and "the ride" money to pick up a good "non-campus" dinner on the way back to school.
We've twice driven up to spend one night in her college town, and I think WE have enjoyed that perhaps more than having her home. When we do that, she loves showing off the places she goes, etc., and we focus on having fun together; in contrast, when she comes home, she spends part of her time with high school friends. When we go up for one night, I'd estimate it costs us about $200 total for gas, hotel, meals.
One small oddity: Her medical costs have gone down. She got sick with -- was it strep throat or brochitus? Oh well, something common -- the second week of school, and when she went to the health department on campus, she didn't have to pay a co-pay. If she'd gone to the doctor here, that would've cost me $30. Also, she takes a medication on a regular basis. I'd been paying $15/month here, but she can get it at the college health center for $5/month. I gave her the cash to buy it, and she made sure to get enough to cover the summer months before she came home. Also, she can get over-the-counter meds for free.
When our youngest heads out to college in a couple more years, we're thinking of downsizing to a condo for our remaining working years. If we do that, I think our everyday expenses will decrease.
In closing, yes, I do see a difference in our budget when our college girl's gone. I think I'll see more of a difference when they're both gone. However, the difference isn't all that significant. We still live in the same house, still maintain the same cars.
I'm convinced that senior year is expensive and college freshman year is expensive . . . but sophomore year is shaping up to be a little cheaper: She already has all her dorm needs, and she's able to get a cheaper meal plan. Next year as a junior, I anticipate our costs will go up. She wants to move to an apartment as a junior, and at that point she'll begin student nursing clinicals, so she'll need school-color scrubs (must be special ordered from the bookstore w/the school logo and the student's name embroidered on the top) and a reliable car for transportation. But then I don't think we'll shell out quite as much for her senior year -- she'll already have the scrubs and the car. This, of course, is somewhat speculation on my part, but I believe it to be true.
Good luck as you begin this college journey with your daughter! Our girl LOVED her first year of college, was very successful academically, and we've loved watching her and helping her.