Sounds a little high to me.  I haven't bowled a handicap league for awhile but in our scratch leagues they are all over the place. 

One of my leagues uses 120 base + 99 pins handicap,
BUT
our handicap is 100% of 230.
So vacant scores suffer a lot, relatively speaking. 120 + 99 = 219 vs 230 for anyone's true average.

How does your league handle vacancies?  For example, our senior league gives a vacant 120 per game plus a handicap of 90 which means they get 210 (with handicap) per game or a 630 (with handicap) series.  This seems to be high in my opinion.  Just want to know how others handle this situation.

According to the USBC Rules a vacant score uses the same handicap as the league, Unless otherwise stated by league rule.

Now the men's league here used a vacancy of 0 + handicap. So say you had a handicap of 90% of 230 the vacancy had a handicap score of 207

Our leagues take average - 10 pins per game.

That's for a absentee (A Player not there) score which is different than a Vacancy score.

Commonly Asked Questions – Rule 105.
105/1 What is the difference between absentee and vacancy?
As defined in Rule 105, Item e, an absentee score is used when a regular member is absent and a substitute is not available. Unless otherwise provided by league rule, the absentee score for each game shall be the member’s current average less 10 pins and, in handicap leagues, the handicap is based on the member’s current average.
 
According to Rule 105, Item d, a vacancy score is used when the team’s roster is less than the playing strength of the league. The vacancy score shall be 120 unless otherwise provided by the league rules. In handicap leagues, handicap for vacancy scores is calculated using the same handicap percentage the league utilizes for its regular members unless the league rules state otherwise. For example, if the league’s regular handicap is 100 % of 220, vacancy scores must be calculated on the same basis unless the league rules state otherwise.