There are plenty of threads about corkage. Folks have all sorts of opinions about it. I want to just put my view out there and ask that you respond politely and without a lot of thread drift into how much wine gets marked up, etc.
A couple of points up front. I bring wine with me about half the time I dine out and look for restaurants that permit corkage. Unlike in some states, here in DC (and now in MD) in order for a restaurant to permit corkage, they have to have an alcohol license. This is in order that there is a trained alcohol supervisor on site. (At least that is the reason given in the law.)
When I have wine in a restaurant, whether I bring a bottle or buy off the list, after the first pour from the bottle, I do all the pouring. I make it clear to the server that I wish to do so. I do this because people drink at different paces, may or may not want a refill, etc. I usually know the others drinking (usually family or friends) and can gauge when to refill a glass. I would also add that I seldom only have one bottle for our party, more like a bottle for each of us if we are having a big meal.
I do not buy "cheap" wines. Inexpensive wines, occasionally, but I see no reason not to drink really good wine. I also tend to buy very small production wines for the most part. (under 600 cases, and in many instances, under 200) My wife says that everyone needs a hobby, so mine is collecting small production wines from CA, WA, and OR. I do buy other wines, but in that instance more for what I like (or my wife likes) than production size. About 20% of the wines I buy lately are French or Italian.
I never take a wine that is on a wine list with me to the restaurant. (That is not normally an issue since most of the wines I buy are allocated and never make a wine list.) If the restaurant does not permit corkage, that is their right. If they do, I expect that I will get serviceable stemware, and if necessary a decanter. Of course, when I travel to places where corkage is not permitted unless the restaurant does not have a license, it is a different story.
I recognize that corkage is not a right and I appreciate when a restaurant permits me to bring wine with me. I expect to pay a reasonable corkage fee, which around here means in the $20-25 range. On the other hand, I also know enough restaurant owners to know that corkage is also a marketing tool. Some restaurants offer free corkage on certain nights when business is normally slow (Monday or Tuesday normally) in order to encourage folks to dine those nights. I also know that it works.
Many of my friends also avail themselves of corkage. There are a couple of things that they say. They like to have wine with dinner, but they will dine out more often at expensive restaurants if they can bring their own wine rather than buying off the list. Many of them have nice wine cellars and therefor have wines that they want to drink when it is mature. Many restaurant wine lists have some wonderful wines on them, but they would be much better if they were 5 to 10 years older. Let's face it, absent buying of the secondary market, most restaurants do not have the space or can afford to buy the kind of wines that really need to be cellared until they are in prime drinking condition. Thus, I can bring in a nice '01 or '02 CA Cab from my cellar that is ready to drink and I know how it has been stored. Most restaurants cannot afford the upfront costs to hold such wines until maturity. It becomes even more so with classified growth Bordeaux or Burgundy or Barolos and Brunellos. Yes there are restaurants that have such mature wines on their list, and when I find them at a price I am willing to pay, I buy them off the list.
Finally, unless I have been to a restaurant enough times to know their corkage policy, I always call to find out about it beforehand. If they say that corkage is not permitted, so be it. And when I call I not only ask what the corkage fee is, but also if there is a limit on the number or size of wines. That way there are no misunderstandings. As I noted in another thread, I have seldom seen the corkage policy printed on a wine list. Occasionally, but very seldom.