You kinda need to have a page for each suburb if those are the keywords you want to target and link them from city pages.
If your site has lots of age, trust, authority, great unique content and power you could do it just with city pages but it will be more difficult and would require a very effective internal link structure that can incorporate the suburb and city keywords anchors without looking spammy to users and SE's and not falling fowl of mega menu problems.
Any way you like. I just know that places as large as Houston or Los Angeles benefit with sector sizes with reasonable distances. I have clients who only want one side of town since it is unlikely anyone from the other side of town (15 miles) will want to spend an hour in traffic to buy their $12 widget. It all comes down to market... and how to market it.
This may only work for less competitive terms but in the past I have had success (inadvertent) from a single page with a drop-down selection box that listed numerous cities. For competitive niches I agree with Conor and the grouping technique mentioned by Tangor. If you make many pages where the only difference is the suburb name then most of them will be filtered out.
I have seen examples in the real estate industry where the webmaster has tried to puff up the suburb pages with local information about schools, churches etc but I haven't seen it work well. If that is the only option left, then you'll need to work on getting deep, relevant links to each of those pages.
At minimum, listing out the names of the suburbs on a page will at least give you keyword weight for those location names. "Offering service to..." would be a good title for the list.
Frankly, though, why couldn't you build a page targeting each suburb name?!? I have a client who has done this (and, they're a small mom-and-pop company). They prioritized the list so that they have built pages for the more-important city sections first, then they build the next set of pages as they're able to -- so, over a long period of time their site has developed more and more highly-targeted pages.
You should also do some research regarding which suburbs are actually searched, and consider this in relationship to what type of site you have. If you have a national directory type site, eg, it's very likely not worth your while to target the suburbs.
If you're a company serving one metro area, your universe is smaller and each suburb becomes a larger percentage of your business, and thus more likely worth targeting.
On national targeting, btw, I've observed that search term vocabulary usage is not uniform across the country (assuming US)... so that extra twist can add to the research you'll need to do.