Don't try to match. It'll just look like a bad patch. Make it look deliberate, treat it as a feature. Have fun with it. Create a border around the vanity and fill the remainder with mosaic tile in the colors of your existing tile mixed with colors of the rest of your bathroom. Make sure you remove enough old tile, linoleum or wood flooring around the new vanity to leave enough room for the border as well as some of the new fill tile to show. Just like with an area rug, you want to be generous in size. If you have beige tile and say, black accents in the bathroom, you might want to choose a solid black tile for the border, then you could use mosaic tiles in beige tones and sprinkel in some black ones to fill the rest. Alternatively, if you find tile that almost (but not quite) matches your existing tile, you could do the border in mosaic tile, or a contrasting rectangular tile and fill the center with the almost matching tile. I only advise you to do that though if the border helps to visually separate the tiles enough to make the slight difference disappear. The sky's the limit. Good luck!

As a rule, BB cabinets and counter tops are separate, but sold as a unit. The usual procedure is to adhere the counter top to the cabinet with silicon. That means simply running a knife between the joint should cut the sealer on the open sides/front of the cabinet. Then pull/pry the counter top free.

If it's a double sink vanity, you want the full 60", and that's even tight for an alcove. Vanities sold online are mostly meant to be free-standing. There's a couple of ways to go for a wall-to-wall installation, where you don't need decorative side panels. What style of vanity are you interested in?

I have a single sink vanity in the bathroom off our master bedroom (which unfortunately is not a master bath) and another single sink vanity (a few inches bigger) in our master bedroom. We are looking to keep the cabinets but replace the counter tops. We have the faucet and above-counter sink in mind. Those would require two cuts on each countertop: one for the faucet and one for the drain. For a visual of the idea here is the sink and the faucet listing on amazon, its the white rectangle sink and the brushed nickel faucet (https://www.amazon.com/gp/product/B018S1Q0VU/ref=ox_sc_act_title_1?smid=A3SE6K3TNDHAFT&psc=1). We are new to do the DIY world of home improvements but we're fearless and love to learn, so beat with me if I lack knowledge of terminology, I like to make up for that with a detailed explanation! So the vanity inside the bathroom is in a corner and touches two walls: the back and right side wall. The vanity in the master bedroom touches three walls: the left and back wall and a right half wall. So I think we will require the backsplash that matches the countertops for the sides and back of the counters. So, I'm here trying to find the best route to accomplish this DIY. We live south of Denver, CO and would like to install it ourselves to keep costs down. In addition to keeping costs down, I've been advised to check out remnant yards of stores that sell/install countertops since we don't need entire pieces like that of a large kitchen counter. Since these two vanities are separate but relate to the same bathroom, I am keeping the consistency across the two. We are not set on the color or the exact rock, so we are open. Please feel free to share any advice you may have! Again, we are inexperienced but everyone has to start somewhere and we are eager! I will post pictures and measurements of the vanities when I get the chance! Thanks in advance!