Get some quotes from local contractors. It's more complicated than you think it is because it involves removing both interior and exterior wall cladding and creating a new header for support over the larger door. Then after installation, you have to reweatherproof the exterior properly and trim everything out attractively both inside and out.

Not sure where in MD you are located, but Windows on Washington may serve your area. Great guy, and he sells "installed" or DIY. On product, for wood the big 3 makers are all pretty decent. (although I only like the Designer series in Pella). Some people like that screen, others don't. I installed one for my parents several years ago, and the bug thing is overblown by competitors with the interior screen. If you want bang for the buck, vinyl can't be beat. They'll generally offer superior performance numbers as well. My favorite is the okna/Himark offering, with a .26 u value, and .06 air infiltration rating. The latter is unheard of as sliding doors go. Sunrise and Softlite have nice offerings as well.

We had Window World windows installed on our entire house. We love them! I ran across this when I was searching for WW to contact them about installing a door. I had to comment. The windows look great. The installers were on time, professional, and did a wonderful job. Definitely not " drug addicts " mentioned in an earlier post. 10 years later and absolutely no problems. I do not work for WW, nor am I affiliated with them in any way other than being a satisfied customer. Why would you think that anyone who leaves a positive comment must be working for the company? Ridiculous. It seems that a few are going out of their way to discredit the company with a mouth full of sour grapes. Maybe they work for overpriced, horrible pushy salesmen, competitors

We will replace 2 sliding glass doors (72"x80") with metal frames, likely original to our 49-yr-old house, because they've fogged and one is hard to move. Our contractor recommends Viwinco and the distributor he sent us to seconded that and showed an S-Series unit (vinyl clad exterior & interior) with Northern Zone glass pkg. We also looked at Anderson Narrowline 200 Series. Is Anderson worth the additional cost? Online I read mixed reviews of Viwinco, all at least 5 years old, along with recommendations for Sunrise (no local dealer in NE Pennsylvania) and Okna. Okna is carried by big box stores but I don't know what model to look for. At our "advanced age," we don't know how long we'll remain in the house. What do you recommend?