From a Real Estate value a separate closed off dining room is becoming outdated and the open living space is more desirable. If you already have a place with a table near the kitchen, then you may be set and what you do with the dining room is negligible. Oldog/newtrick is right that you do not want to affix anything so permanently that a buyer could not remove it. I am sure you have noticed that Real Estate sucks right now so make the place for you and your family to enjoy, you are unlikely to be able to sell your place for what you want very fast right now.
Wet bars are very popular right now, and again depending on the location and the other rooms you have it may end up not reducing the value of the house and even may be able to get 50% of the cost of making the wet bar.
In my last house we put in a wine cellar and a full bar, it was great, we loved it! If you do the work yourself it does not need to be expensive. Here is one trick we used, we used finished bamboo flooring for the bar top, we only paid $1.99/sf for a hardwood top, it looked great and held up well. If you do not like the look of the grooved edges you can put it through a planer. If you want to plane it down any finished hardwood flooring product has Aluminum Oxide coating on the top, which wears tools down fast. Bamboo is a grass, but it does plane and sand well, and it can take a normal stain. If you prefer Oak, again you can sometimes find Oak flooring for less than Oak lumber.
I know that was off topic, but may help in putting the bar together. In other words, put in the bar and enjoy life, no need to have a room that is useless.
Good Luck,
-Ryan