A metal or wooden framed 6x8 sounds a good size. I think that would be a good size for any gardener unless you grow loads of plants.

Personally I'd get the biggest greenhouse you have space for. I only wish our two were bigger...

what do you think about the Nature By STC 6x8? If I had the money I would get a big one for my wife. But im only 22 years old.

If she wants a 6' x 8' then fine. But if she would like to grow a lot from seed, then do masses of pricking out (and even keep non-hardy plants in there?), then I'd recommend an 8' x 10'. I used to have an aluminium greenhouse, then used some money when my Mum died to treat myself to an Alton Cedarwood one . . . it retains the heat much better. AND we were given a massive free cedarwood cold frame with it!

If money is tight the cheaper ones do the job, they are just not as strong and rigid, and usually not as high. Mine was cheap and cheerful and it was fine. She should love you for it anyway - its a lovely present. I suggest you replace one of the roof lights with an automatic opener - they are wonderful and worth their weight in little apples as my Dad used to say. Also get a supply of the little clips for fixing shading netting or bubble insulation, both of which will be very useful.
Very best wishes to both of you, and many happy years of use.

If you are in eastern Washington, Filip, be sure to consider how the greenhouse will be cooled in the summer, unless you just don't plan on using it then. When the outdoor temps hover around 105º F, the greenhouse can crank up to 140º.