I've not been to Chizakaya on a Saturday night yet but have been on several Fridays and never witnessed a half empty room so I wouldn't let that be a deterrent. Other possible options--Owen & Engine, the Bristol, Purple Pig, Maude's, or Sable. All are good spots for eating (including plenty of veg/pesc options)
and drinking but if you wanted to venture on to another spot, the Whistler is great for wonderfully priced and uniquely delicious craft cocktails. All of these places have threads describing them if you use the search function. And all will provide you with plenty of activity--perhaps more than you wish for since packed houses can equal long wait times. Have fun and report back!
"Knowledge is knowing a tomato is a fruit; wisdom is not putting it in a fruit salad." Miles Kington