Double Date Difficulty

My New Year's Resolution was to be more social, and now that we're over halfway through 2014 I'd like to say I've been doing a good job and have definitely established some good hangout habits.
I feel somewhat strange when it comes to making plans: I love my friends, and love going out and doing things with them, but I also love staying home on the couch and not having to put a bra on. I feel am ambivalent mix of anger and relief when a last-minute cancellation comes up, and an equally confusing stress-adrenaline combo when someone texts with a spontaneous invitation.

Last year I would often complain that we never saw my friends, but we spent most of our weekends hanging out with J's family so it's not like we were spending much time with his friends either.
My technique to plan a date would be to send a message to my busy gal pals telling them "Pick a day in August and we'll get dinner. Any day. I'm free the entire month. I am at the mercy of your schedule." Sometimes that would work, sometimes it was so far in advance that one or both of us would double book and have to cancel, and sometimes I just wouldn't get a reply. J's method is to send out a mass text an hour before any given event is to take place. This has limited success because his friend are mostly the same group from high school and therefore talk amongst themselves to create dates with each other, so if married couple A are unavailable, odds are married couples B, C, and the miscellaneous singles are involved.
I like to use facebook messages and events to send invites, but fewer people are active now than when we were all in college. It's frustrating when an event has 30 invitees and only 3 have responded. When I hosted the Hearts of Hope party, I had huge issues trying to get rsvps. I got so many "that should work" replies instead of "Yes I will definitely be there" that I had no idea how many painting kits to order. On the actual day of the party, I had no idea who would be there.

This past weekend, we went out on a triple date to celebrate a friend's engagement to a recently-married friend's brother. We went to a shi-shi tapas bar (pardon me, according to the note on their website, they shouldn't be referred to as tapas since they don't serve exclusively Spanish food, preferring instead "International straight up small plates"), which doesn't seem that crazy except us three girls have been wanting to make a trip to this place for well over a year. The newly engaged friend suggested we go for her birthday in May 2013. It wasn't until I suggested we go there for the engagement and set a date with her future sister-in-law (because we were at a bridal shower and I bugged her to tell me the next Saturday that she was free..no not when you get home, check your calendar now...text her to see if she's free, too. No, not later tonight, text her now...) that we actually went. It wasn't ideal, since they had both worked late the night before and were pretty tired, but it was better than waiting another year to try a new restaurant. We ended up liking the food and really liking the drinks, plus we had a good time pointing out the wacky decor hidden in the corners of the dining room.
While we were out, we made plans to have a Slow-Cooker Saturday at my house in August with a few other couples. It's basically a pot-luck but everything is made in a Crock-Pot and you drink for like 5 hours before you eat. We pulled out our various schedules and picked a day right then and there; the following day I sent a message as a reminder for the date and what we all agreed to make. My married friend said "We should always plan our next hangout before we leave!" and I agree that would make things a lot easier. We'll see how it goes at the end of SCS.

While I love going out to eat, when that's the main event of a double-date the bill piles up pretty quick. J split the bill on Saturday with one of the guys (they decided to treat the newly engaged couple) and it wasn't cheap. J and I are on an ongoing mission to limit our "miscellaneous" spending and my newfound fervor for leaving the house isn't helping us at all. June was particularly tight because we were each in a wedding and had to shell out the related suit/dress/hotel/gift expenses.
I like the idea of having people over for apps and board games versus meeting out at a restaurant/bar, but that's difficult to arrange when everyone lives 30+ minutes away and somewhere out is central to everyone. Sometimes it works out, though- Yesterday I sent a friend a message on facebook asking "When will we have our next play date?" so she's coming over and bringing dessert for steak night at my house this Saturday.

The next big event I'm planning is a party for the first anniversary of my heart transplant in November. I've already starting coming up with a few ideas for decoration/activities! End of the day I'm going to have a good time, but it's important that my friends are comfortable and enjoy themselves in my house. I get stressed out when I'm in party-planning mode because I never know who to invite (and who might be offended if they don't get asked), who will actually show up, how much food to get, and if most attendants will go away happy that they gave me a Friday night.

How far out do you tend to plan things? How do you get in touch with your people to announce a party or a dinner? Would you come to my heart-transplant party?