These are pictures of the front yard:

The planting bed:

The planting bed, sideview:

A view from the porch:

Comments I got among many others include:
They are too closely planted to the foundation (I'll move them further out, 4' from the foundation). Extend the bed to the front of the yard. The bed is informal rather than formal. The formation of the boxwood is too formal, uninteresting, and doesn't compliment the house. Mixing out plants will be good. Get a bigger tree on the right corner at least 10' from the house, and a smaller one such as Hydrangea paniculata treeform on a spot marked with "tree 1" below.

This is the current plot map to scale (1 square=2')

And I drew this one reflecting comments (as much as I could digest):

I'd like to do this semi-DIY and more importantly really hope that I'd be able to recycle plants I already have (8 green velvet boxwood, 4 red/double knockout roses.) This was my first-time-ever-in-my-life plant purchase and I'm having hard time letting go. Including the planting costs, they were quite expensive, too. And I do like the combination of boxwood and red roses.
I think my main question is how to move and rearrange those boxwood and roses around. And the in the meantime, I'd like to choose the right trees. More broadly, I wonder what else should I plant there and how do I extend the bed. I like picking up flowers from a nursery in the spring, so I can plant annual plants every year.

I'd ditch the looping curves. (To me, they seem like a whim imposed for no good reason) Instead use sweeping curves that go somewhere. I'd also ditch the little tree (1) position that will cover up a central feature of the house, in favor of a larger tree at the right side of the front yard that will help the house look nestled in rather than sitting lonely on top of the ground. I know the well meaning advice to enclose the walk leading to the front door with plant material is given from all corners--even professionals--but I would resist listening to it and let the grass come to the fore side of the walk. Drive around and observe the "enclosed" arrangement in real life and see what it becomes in a a relatively short time and then, down the road. It's practically a "Do Not Enter" sign.

I'm imposing these ideas on your plan so you can see generally what they look like in that view. Everyone here knows I show the basics. You can adjust, add plants, subdivide shapes (in a geometrically compatible way,) delete, pick species that spins your beanie or whatever you want ... at your own risk, of course.

And Thanks Laurie! Everything you said is so right. I'm googling boxwood & rose pictures, and they just look lovely.