downtown Toronto is pretty big - are we talking Financial district? near the university of Toronto? by the Don Valley?
The one area I would actively avoid (I refused to rent there even though it's cheaper) is bounded by Bloor on the north, Church on the west, approx Queen on the south and approx Parliament on the East. Unless it's changed a lot in the last 5 years significantly I'd stay away. (The area around Jarvis/Dundas is where I always saw prostitutes).
Not to be a downer, but 30 minutes commute means your options will be a lot more limited! Unfortunately Toronto transit is nowhere near as developed as most other major North American or European cities. Train wise, there are TTC subway trains (3 lines only), and the GO train which is a commuter train, but again you'd need to be pretty close in, unless you mean 30 mins plus walking/driving to/from station time. The bus system is a lot more extensive, but can be somewhat unreliable, especially in winter. Streetcars in the downtown core, and stretching out from the core a bit on certain lines.
I used to live around High Park in a couple of different areas, which personally I liked best of all the places I've lived. Very family friendly, close to a nice "village" feel area on Bloor Street, easy commute into downtown, close to Lakeshore/the highway, close to High Park (one of the more significant green spaces in Toronto).
I always made sure to live close to a bus stop or subway station, and I didn't have a car for most of the time.
I lived in the Village (gay neighbourhood), which is right in the center of things, for a couple of years but that was when i was more or less single. Completely different vibe - trendy shops/bars nearby in the Village side, and then the regular downtown core on my other side.
I did also live off Queen Street East (Leslieville area) - not my most favourite area, a bit more run down but there are nicer parts than where I was renting. It felt further away from downtown for some reason, but it's close to things like Greektown, the Beaches.
And I lived west, as in Mississauga and Burlington. Mississauga is a huge suburb and if your husband doesn't mind the slightly longer commute, I'd seriously look there (spent my teen years there). Lots of very good areas with very good schools, and if you stay close to a major bus route or near a GO station, the commute won't be too bad.
Further out, Burlington - I lived there when I was a poor graduate working and trying to save money. But the commute can be pretty rough - train itself isn't that long, it's the additional time spent getting to the station etc. It's developed a lot more since I lived there, so the community amenities are much better.
Basically it all depends on what you're looking for, and what lifestyle you want to live. Do you plan to live in an apartment or try and rent/buy a house - single family or townhouse? Do you want to renovate? Do you plan to have a car? More than one car? etc etc. What's your budget? How old are your kids? Do you want public or private school? Do you want an IB school or a regular school state school?
House prices in the GTA have skyrocketed in the last 10-15 years, so you may get less for your money than you expect.
In NW Mississauga (Meadowvale) www.realtor.ca/Residential/Single-Family/18224776/3754-ALTHORPE-Circle-Mississauga-Ontario-L5N7G4-Lisgar?utm_source=RealtorWeb&utm_medium=Share-FBListing&utm_campaign=ListingLink
I saw a listing for a really nice looking end unit townhouse in Scarborough (NE Toronto) near Markham Rd for $549,000 but can't find the link right now.
Your DH should also ask the employer if they have a real estate or relocation assistance program for new hires.