What an amazing experience for your parents... I can imagine how full their hearts were! I did a similar thing a couple months ago. Family (4 + my wife) plus extended family (3 more) all went to a 'nice place' for dinner that my parents particularly like. We all had a lovely long meal... wine, appetizers, main courses, desert, etc., and like two hours of conversation and laughing. I'd slipped our server my card before desert even hit the table, so when my Mom inevitably went to pay (as she and my Dad had planned/assumed they would), their card was refused because the bill was already covered. They looked down the table and saw me signing the check and handing it back to our server. The total was something like $525, all in, with a generous tip. I paused for a moment when I got the bill, thinking "woah... I figured we were in the $380-450 range". Then I realized the difference between my guesstimate and the actual total was around 2-3 hours of work... and I had to pause a moment and think about that again... it put zero stress on my finances to throw another $150 on a restaurant tab. I've spent the majority of my life living pretty much paycheck to paycheck. It's only the last 4 years or so where I have finally had a safety net and four-digit balance in my checking account. It's nice to be reminded of the privilege I have had, and to share that with the ones I love. And yeah ... my parents got misty-eyed at me picking up the bill, too. They are also proud parents.
That sounds like a fantastic night. Topped off, we had wonderful service all throughout the night. The place started off really busy but our server was on the ball the entire time - remembered everything, even the smaller requests and weird drinks we were trying and who ordered what. You know how sometimes the staff will come along with meals and say the name so whoever ordered it can indicate it was theirs? No need for her, she just scooted by and popped them down without having to double check - spot on. At the end, I mentioned to her at the counter that it felt odd not being able to tip (it's not done here in NZ) for such awesome service and all she said was: "Just come back and eat here again, that's our mark of great service". So we did!