Congrats on the house!
I wouldn't personally put soil over liner, normally you would plant through liner (put it down and then cut an 'x' and peel it back to plant in) and top with gravel or bark to weigh it down/make it look pretty...
What sort of plants are you thinking? perennials like lavender or roses? or some bedding plants just for the summer?
I've always done well with snapdragons and fuchsias (totally slug proof) and geraniums are really good for people (like me) who aren't good at regularly watering them.
You could even do some sweet peas, grow them up some canes (make like a teepee with some bamboo sticks and string) and just pick them regularly to keep them flowering.
Gardening is just trial and error, plant what you think looks pretty and see what happens
Good Luck