My husband and I eat out every now and then - like other posters, I think I cook fairly well, so my standards are high for what I expect to eat at a restaurant.
We've eaten at hole-in-the-walls and 3 star Michelin restaurants and had the same quality at both. We just ate at a beach shack and had some awesome food - turns out the chef was French and knew how to do sauces (she had a lemon sauce on the fresh grilled tuna that was amazing - olive oil and lemon juice, however, cooked and emulsified just so). She also served lamb shanks in an amazing tomato based wine sauce - it was obviously slowly cooked - and fresh herbs make a huge difference in any cooking. The mashed potatoes had either cinnamon and/or cumin in them - so the Arabic influence was there (like Moroccan spicing - adds a bit of depth to the flavors over time). It might sound weird to use those spices, but in little bits it perks up the taste buds.
That's what I've found with the truly great restaurants - they have studied the biochemistry of the taste buds and have mixed flavors to enervate them so that your dining experience is enhanced. Like any sensors, there are resonant frequencies, so either using those or avoiding them is how you can change the dining experience. However, that is also true with comfort food - I'm a BIG fan of macaroni and cheese in all forms: pasta alfredo is just an Italian version of mac and cheese, kasespatle is the German version, and so on.
Back to the topic - so, depending on what you are looking for taste-wise, restaurant quality and prices can vary widely. I enjoy most of it except for most fast-food. What I use restaurants for is not only for a nice dinner with my husband and/or friends, but to see what other taste combination I might be able to do myself in the kitchen. I've also noticed that my husband and I have some very good conversations while eating a good meal and it cements our relationship more.
Tipping - uhh, when did it become 20%? I guess after living in Europe for quite a few years, I've not been around to see that. Frankly, I've noticed the food, service and prices are so much better in European restaurants and one does not have to tip but usually rounds up 1 or 2 of the denomination for good service. I have worked in restaurants in the US and understand the ethos, however, one was supposed to report the tips anyhow and the managers (even in the 70's) as well as the tax man could report out your tips to the IRS nonetheless - don't see how that justifies an increase to 20%,