Can we see the other 2 sides of the room? Is that a pile of cushions in the corner? You are right that black is not coastal, but you have a lot of black that is going to stay i.e. TV cabinet, table and chair under the artwork, hanging lamp, picture frames. If all those black things stay, then switching out the coffee table and end table isn't going to make enough difference to justify the expense. As it is, the tables look good with all the other black that is staying in the room.

You can still have an attractive look using the colours of your rug and artwork, and still keep the black and your sofa. I would add more items in a dusty turquoise blue to repeat those colours from your art work and rug. Maybe even paint a wall or walls in that colour to make it your primary decor colour.

Nice start can you just paint the top of the coffee table and side table white? add some pillows to incorporate the colors and maybe a throw. Maybe something like this to the table to tie it all together.

I'd definitely add pillows. Different colors: yellow, white, patterns.

Do you have a place (garage or basement or back yard to paint the metal furnishings white instead of black -- or invest in a plastic painter's tarp and paint them with a brush in lieu of the easier spray paint? Adding some beach vibe to the cushions with iron on patches stitched to them could further that objective for the room.

https://www.google.com/search?q=iron+on+beach+appliques+and+patches&client=firefox-b-1-d&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjH7ubI9tLqAhUlZjUKHbkIB2EQ_AUoAnoECA0QBA

If those cushions are "extra seating" for visiting youth or limber young adults, see if several of them would fit beneath the coffee table.

If you change out your throw pillows, you might keep white or a really light blue in them -- or jut add a cover or patch/badge to one side of those you now have.

Rather than put a tv on a heavy piece of furniture, consider a portable stand -- something a summer beach rather than a full time residence might have.

https://www.google.com/search?q=portable+tv+stand&tbm=isch&ved=2ahUKEwia0tXK99LqAhXMFN8KHc30DSEQ2-cCegQIABAA&oq=portable+tv+stand&gs_lcp=CgNpbWcQDDICCAAyAggAMgIIADICCAAyAggAMgIIADICCAAyAggAOgYIABAHEB5Q0CNY7C9grz9oAHAAeACAAXeIAZAHkgEDNS40mAEAoAEBqgELZ3dzLXdpei1pbWfAAQE&sclient=img&ei=4-MQX9rUO8yp_AbN6beIAg&bih=654&biw=1366&client=firefox-b-1-d#imgrc=dAiT69MgIL8VfM

Is your coffee table one with a Formica top attached via screws to a removable metal base? If so, you might swap out the current dark top with a light colored built board ( preferably one with rounded corners) and/or you could add a (carefully measured ) glass top to what you have and fill the area beneath the glass with beach pictures -- instant lighter look.

You could have a glass cut to fit your table much as the black wicker table on this page:

https://www.fabglassandmirror.com/glass-table-tops

Getting the paint to adhere to Formica or similar tabletop material can be difficult and the paint can scratch easily.

If the board top can be removed from sturdy metal frame and be replaced, that could be a better idea:

https://www.lowes.com/pd/Common-3-4-in-x-24-in-x-6-ft-Actual-0-62-in-x-23-25-in-x-6-ft-Pine-Board/50053145

There are oils and stains intended for boats that absorb into the wood to seal it that might work for your finish -- the kind you rub in with a cloth -- no paint needed on the top. Know what kind of wood you have and read the product label. Do some You Tube research. You'd need a painter's plastic to protect your home from the drips.

thought you might consider some new pillows to bring the vibe to your sofa. a few different directions you could go.

some thoughts on an accent chair

some of the coffee tables have a matching side table if you want the same style, but here are a few more options

I see your colour scheme more as a Southwest scheme. Similar to coastal in its use of sunset colours, but with darker woods and less white. Middle Sunset scheme.

Sunset Colour Colour scheme #3 with turquoise

I love so many of these ideas! Especially like the Howze coffee table from Wayfair. It has the look and color of driftwood, which is cool. And adding the turquoise blue as an accent color is great. I also love the orange end table. I will include photos of the other side of the room soon.

The cushions in the corner are possibly for our teens to hang out, maybe for a game night, but since that hasn't happened yet, I may get rid of them. If I keep them I'll likely cover them with brighter fabric.

thought i would check in to see how the decorating is going and if you have made any progress?