First, make sure you have a good, functional layout. If you post an overhead, 2D, to-scale view of your space / layout, you'll get excellent help here!

Then, I'd want to take a sample cabinet door to the stone yard and look at various slabs. You may get more love here for natural stone, but plenty of people have quartz as well. One consideration is whether your layout will need seams (for example, corners or a long island.) If you need seams and choose a slab with prominent veins, you'll want to be sure you are involved in the templating process and you'll want a very good fabricator.

Backsplash is chosen last, after your cabinets and counters are in. Bring home many samples and folks here can share their thoughts. But don't be in a rush with it -- you'll likely live with it for a long time. (If you're new to picking out tile, I posted this thread to try to help others avoid the mistakes I made not paying attention to tile variation.)

I understand being overwhelmed! There are SO many decisions, and it's an expensive project! I used a spreadsheet to keep track of ideas and costs (appliances, lights, tiles, pulls, plumbing...)

You have found a good spot for getting help! Here's some more info:

• New To Kitchens?
• "Ice Water Stone Fire"
• About halfway down in this thread are some very helpful comments by @Buehl regarding drawers for lower cabinets (most of us are team drawers! So handy!) and space planning. This is all very good info to have and use during your design phase.

Again, I get that it's overwhelming! But the knowledgeable folks here will help you get the most from your new kitchen.

Switch to granite.

First of all, work with a Kitchen Designer, and NOT a cabinet seller, who is only worried about their little corner of the sales world. A Kitchen Designer, will help with all aspects of the design as a whole, from the functional to the decorative.

Your designer should help navigate the options for the countertops. I find that if my clients feel overwhelmed, then I as the designer need to slow down and reset a few things so that isn't the case. You shouldn't feel overwhelmed yet (or ever, hopefully)!! For basic neutral quartz, I like Liberty Gold ONE Quartz - Marble Look - Liberty Gold (daltile.com) or honed Cabrini Grey ONE Quartz - Concrete Look - Cabrini Grey (daltile.com) It's a warm grey, trending more taupe geris, than cool grey which tends more blue.