I would spend more time on custom descriptions for the ones that you have reviews on. The goal would be to have as many citations with gold stars as possible rank high for your brand name on Google. That way when customers search for you, they are blasted with nothing but gold stars.

This brand name is a good example: ME Contracting

One thing I have found with all these local citation building services is that they focus on the big core group of directories that apply to every business but they leave out the niche directories that exist for each vertical.  I think the niche directories are really key to helping Google categorize your business better. One tool I've been just recently using is Link Prospector. For $1-2 you can run a report that gives you a list of the niche directories related to the keyword/industry you are looking to rank for.

If you do a report for the directories category and list the keywords (include the cityname) you want to rank for, it will pull a list of all the directories related to that keyword/industry. So, for example, if I was a plumber in Seattle I would list "plumber seattle" as the "phrase".  Whitespark helped build this tool as well.

We also use Moz Local. It's really fast and easy to use. Much cheaper than Yext.