I went on one final beach trip with the full family while I was in my long limbo in-house separation. I had incredibly high hopes, but it was miserable because the (now) ex was miserable and acted like she was younger than out youngest and made it very clear that she was uncomfortable and wanted to be anywhere else. How about a trip with just you and the kids? I did that, too, several month further into our in-home separation, and it was awesome -- one of the best weeks of my life. It was very healing and reminded me I can parent on my own, which I needed to remember, especially at that moment.
The only other thing I'd say is that, should things go to divorce, you definitely don't want to be saying things to your kids afterwards like you did everything you could. That will cast your ex in a bad light in front of your children, and that's a cardinal no-no for their healing and development. Even if she deserves every bit of it, you have to avoid the temptation of doing it. No, just live your life now so that they'll KNOW you did all you could and leave it at that. And they will know, especially at their ages (same as mine, BTW).
Me: 46 W: 44 Married: 17 Together 21 D13; S10 BD: 03.03.15 (Not attracted to you) Almost 2 years trying, alone, to save marriage Status now: Divorced (effective 06.13.17)