My beds are 20 ft long, too, but I only keep one or two pieces of row cover long enough to cover a whole row. Most of the time I need to cover smaller plantings, so the covers tend to get cut up a bit. In years when I'm organized, I tag them by size when I put them away for winter storage. My collection is a real mix of row covers, recycled sheer curtains, tulle, and other such stuff. Here is a link that might be useful: sewing row covers

I am a fabricator. There are often at least a few options for seam locations. Seam locations in homogeneous material (little or no movement) aren't important if the fabricator is skilled since such seams will be hard to spot unless looked for. There are various opinions on seaming at a sink. We don't do it for the following reasons: 1. The sink would normally be the busiest place in the whole kitchen so why put a seam there. (note if the sink is a drop in then most of the seam would be covered by the flange on the sink and the rails remaining after a drop in cutout might be too thin to allow moving the part without seaming.) 2. The vacuum cup/ratcheting device used to make excellent seams cannot be used to seam the sink rails. This doesn't make it impossible to do a great seam at a sink but it definitely makes it more difficult. 3. Fabricators like seams at the sink because it mostly eliminates the risk of a cracked sink rail which can easily cost the fabricator a couple of thousand dollars. Good for the fabricator but not necessarily the best option for quality.

I'm in the middle of doing this right now for our diy kitchen. There is a large dealer - wholesaler - in our area with a huge warehouse. The slabs are tagged with price categories, but they won't sell directly to customers and they won't disclose the actual dollar amounts. They told me that the ultimate price varies depending upon which fabricator - cutter/installer - one uses. What they will do is send a list of the slabs that you have selected to any number of fabricators of your choice. They also won't help you pick a fabricator or say which are good or not so good. They would anger their client base if they did so. They will say that some are more expensive and some do better work. When you go to a fabricator, they will also have a selection of slabs, depending upon the size of their facility. You may notice that the slabs have paper tags indicating which wholesale yard they came from. There are typically slabs from several dealer/wholesalers at a fabricator's site. The fabricator may buy and import directly as well. I just spent many days with a friend who was looking for remnants for two bathrooms. It was a good education and a dry run for me. Got to browse with no pressure, and learned about the various places in our area.

We are nearing the end of our DIY kitchen remodel. We just put the counters in yesterday. While it takes time and a level of skill that is uncommon, the satisfaction and money saved is so worth it if you can pull it off. We bought our inset Medallion cabinets at Just Cabinets. It is a chain that I think is throughout the northeast. I don't think our salesperson had ever sold inset cabinets to a customer before, and although they feign knowledge, they are not kitchen designers. So go prepared with your design based on the manufacturer's spec books. Had we not DIYed, we wouldn't have had the money to get so many of the wonderful things we have. But we paid for them in stress, hard work, and research time. The order from Medallion/Just Cabinets was packaged well and arrived in a reasonable amount of time. We used Hardwood Lumber Co for the countertops (butcherblock), and they were so helpful and easy to work with. The counters arrived SO fast and in great shape. We got our farm sink from IKEA; it's called Domsjo. I found it easy to install compared to others because there is a sort of false front that covers your hand-cut sink opening.