This made me think about the number of times I said, "I call you," or "we'll see" without thinking about it. It is kind of like a reflex sometimes. "Friends" actually did a funny episode about this issue. Chandler wanted to break up with Rachel's boss but had trouble walking away and not saying, "I'll call you."
When I am serious I usually say I'll call you by next Friday or something specific. I also usually ask the other person, if they haven't heard from me by then to please call me.
My ability to have a serious conversation about this stuff is directly related to how stressed and overwhelmed I am at any given moment. My Dad just died in March after being really sick for two years. I have made more calendar screw up in the last year, than I think I have the rest of my entire life combined. Some times people need a little understanding.
I don't know about where you are but we have only been out of school for four weeks. That isn't that long.
Lastly, my daughter is 10 years old, and one thing I have learned is to try to set up a few specific plans for the summer before school ends. We usually try to schedule a sleepover with one of her friends each month during the summer, so she'll be sure to see them a least a little.
When I was working, we just didn't see the school friends over summer. Mon-Fri she went to camp, and the weekends were all the things that needed done for the next week, just like during the school year, or getting ready for our one yearly family vacation that usually took place in August.
Now that I am not working, we are around but few others are. We tend to do stuff, just the kids and I during the week. The pool is a big one and she can usually find her friends there. No plans are actually needed everyone just turns up there at some point.
Regarding people saying they'll do something and they don't. I guess I see "I'll call" as a more general statement without an expiration. That is very different than I'll pick you up at the airport Saturday. I would never not pick someone up at the airport if I agreed to it. I might say "I'll call" without really thinking about when I'll get to it.
Thanks for making me think about this some more, I really don't mean to upset people by not calling quickly.