If you go to the high school I did, then you're getting to start the school year this week. While every school year is important, if you're a rising senior than this year will be unlike all the rest.
First off, the minute you mention you're a high school senior, in any situation, people will ask you about college. It just happens. They'll ask where you want to go, what you want to study, if you're excited, etc.. One thing you need to know is that it's okay to not have any answers to these questions yet. Up until May 1st my answer to where I was going was just a shrug and a noncommittal, "Not sure yet." And yes, there will be people who make their decisions before they even apply, but there's nothing wrong with taking your time. Don't let anyone downplay this decision or transition to college, it's a big deal.
Also, make sure you understand that this decision is yours and yours alone. Different people will have different opinions, and it's fine to consider them but don't let those opinions make you feel as if you're wrong for thinking differently. You don't have to justify your decisions to anyone, maybe one school just feels right. Apply to a lot of schools, ones you're interested in for even the smallest reasons, and then don't worry about it. However, it's important that you don't put all of your time into worrying about next year as senior year still matters.
Everything you've ever heard about senior year is probably true to a degree. There is senioritis and it will affect you, it's best to accept that now. It may be different for everybody whether it's skipping classes or just choosing not to do an assignment because your grade can afford it. Honestly though, I didn't feel more stressed during the year than in the last three weeks, and had already gotten into college and finished that decision. Regardless, it's important that you don't let this final year get clouded by tunnel vision looking towards graduation.
You may not realize or think so now, but there are things about high school you'll miss. The simplicity of just being able to walk through the empty halls or the excitement or relief at seeing you have a sub that day. The simple joy of remembering it's Friday and it's a three day weekend. These are feelings that you've become so used to not only over the past four years, but most likely ever since you've been in school. While you may be sick of some aspects of high school now, you need to make sure you don't belittle what you're actually giving up.
Take a second to think back to freshman year, a dark time I know, but think about how different you were. Back then in those early days you most likely knew just the halls that go you to your classes, nothing fancy because of the off chance you took a wrong turn. Compare that to now when you no longer have to even look at the room numbers and you could probably map out the whole school using colloquial terms, whether they be "four corners" or whatever terms your school uses. Those four years are where you have grown into the person you are, through many subtle, and not so subtle, changes and influences.
So here's my advice to you. Enjoy this year while you have it. It will be riddled with "lasts", such as last cafeteria lunch, last class with this teacher, last assembly, etc.. Treat each of these with the importance they deserve. That being said, don't let this year be going from one last to the next. Enjoy the in-between. Enjoy the days where nothing special in particular even happens. Try something you never have, join a new club or team, take challenging classes, and make the year something to be proud of, something to be missed.
Enjoy the simplicity of the school you've all become masters of. Look at all the freshman whose journeys are just beginning (or ignore them like I did, dealer's choice) and prepare yourself to say goodbye. The end will come, and no matter what someone says, it'll be bittersweet for everyone. But don't let that stop you from enjoying it now and looking forward to the future.