My husband moved to my state before we were married. So here we live happily. However, his family still lives in his home state and we often visit. His home state has awesome things not native to my home state — wild berries, beach front lakes and it's a nature lovers dream! But whenever we visit, we always have to take his family with us wherever we go (my mother-in-law specifically).
This isn't really a bad thing, it's just that we are expected to be the ones paying for everything: food, outings and even driving them in our car. So wherever we go we have at least three extra tickets (or whatever else) to pay for. We stopped staying at their place so we won't feel obligated to take them out every time we leave the house, but still we don't get the freedom of just enjoying ourselves with no obligation. So my question is this. Our next trip up is one we want to keep to ourselves. Staying at a friend's place and telling no one in the family so we can just enjoy what nature has to offer and keep to our budget. But as it is a small community there, chances are that they will find out eventually and feelings will be hurt. Should we just tell them before or just let them find out and explain then?
Don't lie and don't sneak around during your vacation hoping you don't accidentally run into your in-laws. That will only cause way more trouble for you (and hurt feelings for her) down the line.
I suspect that your mother-in-law is really excited to see you and her son and wants to spend as much time as possible with you while you're in town. This is understandable. You are the ones who need to set limits (if you want them set), but ignoring her is not the right way to go about this. It seems like you used to stay at their house and have recently started staying with friends. That seems like a step towards independence. How did you manage to make that transition?
Here's what I think you should do: call up your in-laws and tell them you'll be in town and you'd love to schedule a few activities in advance to do together during your vacation but that you're also planning to spend time with other friends. You can see them a few times for meals or other activities and then do your own thing the rest of the time with no guilt. If you don't want them to come with you, just don't invite them. If they try to invite themselves, say, "Sorry, not this time. We'll see you tomorrow for lunch!"
One more thing, why you are expected to pay for everything you do together? Has anyone ever brought this up? It sounds like the costs are adding up for you and, rather than cutting off all contact, you need to mention that the extra expenses are draining your vacation budget.