Quoting Jenn O:" I need some bedtime help. Claire is 26 months and a couple weeks ago she started getting close to climbing ... [snip!] ... terrible. But being by myself, I don't know what to do. I'm trying to nurse Theo to sleep at the same time and it's a mess. "
Our kids are the same ages and my husband works second so I do bedtime alone and we're pretty much in the same boat
Ok, what we do here, is that I get my son to sleep first, then I lay down with my daughter. If I try to get them both down at once, they keep each other up and it is a nightmare.
I would get her a twin anyway if you can afford it. Then you can lay down with her in a separate room from your son and not risk waking him up again.
The spazziness, my daughter totally does. Sometimes a massage helps, I start with her feet, and then get her legs. Sometimes I have her lay on her belly so I can rub her back. Sometimes, it doesn't help at all. But it's worth a try. Being over tired=adrenaline which is bad for sleep obviously, haha, and she's probalby over tired anyway if she's been sleeping like garbage, so it is a cycle. Either way, a massage is super relaxing and a bonding time before you go through the trying process of actually getting her to sleep.
Also, if she is going to be up late anyway, instead of trying for hours, just try an hour or two later than usual for a couple nights and see if she passes right out. Then you can move her bedtime 15 minutes earlier every night until it's back where you feel works best for everybody. That might reset her body into remembering bedtime is a time to lay down and sleep, not see how long she can fight.
Those are just a few things we have tried, if you have specific questions or if you think those won't work, I have a million more suggestions. We've tried pretty much everything around here because we have sleep issues. Sometimes they just evolve and a lot of times what works one night doesn't work the next night (or ever again!).