Could be a night out or cooking for yourself. What do you spring for if you're treating yourself? I have a couple of favorite restaurants I only visit on occasion. They're not crazy expensive but more than I usually spend eating out. It's nice to have a great meal and drinks without worrying about the budget too much. If I'm staying in, I like to grill a nice cut of steak with a bit of shrimp served with steamed veggies, mashed potatoes, and share a nice bottle of wine.
My splurge dinner would most likely be going out to eat at a restaurant that I know is really good. We have a few steak houses in the Cleveland area that are really good, one of my favorites being Red The Steak House. It's a suit and tie type of place, and the steaks are around $35 on up, not including sides, which I believe are around $8 a piece, but everything there is cooked perfectly and the service is fantastic. Plus it's a relatively small space, so seating is limited - which is a good thing because the kitchen cannot get too swamped at once, and your servers can attend to you better instead of juggling 5-6 tables at once. For something less expensive but still a bit of a splurge, I would hit up some of the other fun restaurants around here, such as Tommy's in Coventry (which is kind of a hippy area) which features a mainly vegetarian menu with a great selection of rootbeers, or Micheal Symon's The B-Spot for some great burgers. If I was going to cook at home and splurge, I would probably make something similar to what you suggested, with a thick cut ribeye from a local butcher. Otherwise I may opt for some pricier cut of fish such as Chilean Sea Bass.
If I were I a decadent mood, I'd usually just go to a nearby buffet but I'd pick one that was of higher quality since the cheaper ones usually don't do much for me. If I'm trying to save but I'm craving buffet I'd go to them, but if I had a bit extra I'd splurge on a more expensive one. I also like splurging in Chinese restaurants because they have so many varieties in their dishes that I don't always get to taste them all, but if I were in a splurging mood then I could buy a few more dishes than I would on a regular day.
I rarely eat out but I do like to cook. So my splurge dinner would be pizza, I love making it. Most of the money goes into quality ingredients like good cheese, meat, olives ... and the list goes on. After the dough is done and has rested for a while I get on decorating and baking the result. Once I bake a few trays I have enough for a whole day of pizza binge. All that's left is to find some movies and I'm done
