Can you provide a picture of where you're planning to put the paper vs the paint? I think, myself, that wallpaper should be continuous along the length of the wall, unless there are architectural features that break up the line of sight.

As I said before keeping clutter under control is the key, get lots of storage ,you said cost is I s an issue. Look at IKEA they have solutions for wall units that you can get in different colours and that in itself will brighten the place. You would benefit from a buffet next to the kitchen /dining area or a large wall unit with lots of shelfs and drawers, coffee table with storage drawers , storage unit with baskets for kids toys and school stuff, once you have this under control start adding rugs if think you still need it. By the look of it you have small kids get them to put things in appropriate place and get some funky coat hangers in the entrance so they can hang hats and bags etc.

The mirrored wall certainly gives you a 'wow' factor and the floor is stunning. I wouldn't do a textured wall paper or metallic, I think you'd end up with too much going on in a small space. If anything I would perhaps paint the white wall in a very light grey to pick up the grout in the floor tiles.

Hi Betty, There are lots of in between wall paper styles out there. We have a few examples of wallpaper feature walls (in a large room) or all walls (such as in a powder room). Here is the powder room link: https://www.houzz.com.au/photos/matilda-place-contemporary-powder-room-sydney-phvw-vp~92259318 I'll send through the other links in a few minutes. Hope these help to give you other ideas! Good luck. Cathy