The on site hotels are great, but no one on here can provide you the "right" answer. The "worth" of on-site hotels is purely subjective.
I love staying on-site, but to me with my current situation in life they are not "worth" the incredibly high prices. The only real benefit is 30 minutes of EE per day, which requires you to expend considerable effort to benefit from (like being at security check by 6:45 am).
I plan to stay on-site more often in a few years when my kids are older (i.e. no longer napping). Right now, I can stay 5 minutes away from the gates on Harbor in a multi-room suite hotel for significantly less cost. When my kids are older and it's not a huge deal to all stay in the same room, the "worth" of staying on-site will be greater.