MIxed sizes of cabs are very common.

Look on Houzz, or here, or the finished kitchen blogg. You'll see many examples.

The main design thing to watch for is where the paneling (if the cabs have pabeled sections of the doors) gets out of proportion with nearby ones due to different sizes.

For instance. if the cabinets have a predominently vetical look to them, but a wider one would take that vertical orientation and draw it out to make it look square-ish. In that case the door should have two panels to maintain the verticality.

Or if the the cab is so narrow, that instead of being proportinal the cab would look like a skinny-minny version. In that case some times a slab door works best for that single unit. (This is more common on lowers though, and is often handled by making the door into a differing deisgn resembling a column.)

Symmetry is nice, but don't let it drive you into having non-functional cabs. The overall mass of cabs needs unified scale and coherence, but the individual units don't require that much bookmatching.

L.

Ditto
Most renovations are harder to have same size cabinets and function is another issue - you don't always want the same size cabinets.
i do question the 45 inch cabinet- Are you going frameless - as if you get that wide, you will most likely need a support in the middle if over 36 or 42 depending on the company.
I would add that the upper and lower lines should coordinate and balance.
For example, I do have 42 inch lower and a 36 inch upper - but it is centered on the 42 below and doesn't stick out.
This is the only cabinet run with variation.
The other uppers and lowers are the same size doors/drawers to add symmetry.
Post a picture for feedback.
Also feel free to take a look at mine - I have a wide variety of cabinet sizes.
http://ths.gardenweb.com/forums/load/kitchbath/msg121427088941.html

assuming they are all standard 30 in height??.....ditto the comments about 45 in cab. Why not get matching door sizes-if you need a smaller cab-say 15 inch, then a 30 in dbl door will provide two doors that match the 15 in.... or 18 in single door with 36 in cabinet with dbl doors. Getting door sizes that don't vary so much usually can be achieved...the symmetry issue,as in what flanks windows or hoods or lines up with base cabs can be important,but mostly in higher visual areas.... . A long wall run with several cabinets can be arranged with really similar door sizes, even with stock cabinets.....it might be worth some scrutiny of the door sizes. Better yet, what do you want to store in the locations?.....A 36 in dble door cabinet with no center stile is a good cabinet for lots of dishes near the dishwasher. A 15 in cabinet can be good for spices near a range.....a 24 in dbl door vs. 24 in single door can be hashed around as to the pro/con of doors in one configuration or the other. After getting a general wall layout and door size congruence, I think I'd be more interested in the base drawers- the width or choice of 3 or 4 drawers per stack...the budget money will be heavily used on the bases but well worth it for drawers....is she giving you the sizes you want for drawers? do you know what goes where?....not every stack of drawers needs to be 36 in wide....symmetry is less important on base runs vs. getting those drawer sizes how you want.....is there a roll out pantry base in the mix?