As a cabinetmaker, my thought is to build but make sure you build to accomidate future purchases / upgrades.....

If you can build it build it. We built ours in 2 pieces (we also have a 50" Samsung. If we change it down the road, we just have to adjust the top, and we have it already worked out on how to do it. When we purchased our TV in April 05, there wasn't too many enterainment units for big screens, however that has since changed.

You have a nice big space for it, our room was cut in half due to the door in the middle of the room, so I had to design a compact unit. You'll have more designer choices.
We are going to also add a small wall hanging dvd cabinet to match, to the left of the unit. Woodworking is one of our hobbies, we are not pro's.

{{gwi:1538427}}
Joann

IMHO, I think it's better to go with component pieces that offer flexibility. I know of many people who bought/built entertainment centers and then were stuck when they wanted to replace the TV or other components. At least with pieces, it wouldn't be too hard to move things around.
A company I used was Salamander.

Here is a link that might be useful: Salamander Designs

My decision on the entertainment center (remember...it is within a media niche alcove and not freestanding).

I decided to go with furniture versus a custom built cabinet. Reason is that I was able to find a great looking piece that only has 3" clearance on each side....has excellent legs which elevates the credenza above my Zanella maple wood floors (if I did a custom built, it would have not only hid my floors, but probably damaged it).

What else I like about the furniture piece is that I was able to get away with a different look and feel as I already have built-in bookcases...which I would have had to replicate in terms of style to make the room look right.

Biggest thing for me is that I am concerned that as TVs change...furniture need change. And I feel that I have much more flexibility by going with my furniture.

If someone shares with me how to copy a picture here into the message text...I will share an image of what I did for my entertainment center.

Thanks for everyone's assistance.

I would like to see your pics
Upload your picture into photobucket.com
under the pic will be three captions
choose tag (click on the white next to tag so that it is highlighted then right click and copy
Paste in your message post

My DH is not a fan of a media niche. It seems they are often weird sizes, weird locations, or improperly vented. Can you put a plant in it and move the tv elsewhere?

There are some really nice all wood options that I found...

Here is a link that might be useful: TV stands