I"m sorry the girls have been sick and hope they're better very soon!
Once a child can get out of the crib, it's time for the crib to go. I'm no fan of crib tents either -- if they are going to try to escape, a tent poses another hazard they could get tangled in, in my opinion.
Put up the side of the crib. Now look at the distance from the top of the raised crib rail to the floor. Imagine your 23-month-old falling that distance. Pretty far for a small child, isn't it? If she falls on her head or neck it could be disastrous. That's why I think once they are climbing out it's time to end the crib. A friend's 18-month-old was climbing out and fell and broke her arm - it could have been much worse.
Whether you go with toddler beds, a regular bed mattresses on the floor (an option I know some parents really like -- no worries about falling out of an adult-height bed), I'd say, goodbye crib. It will be tough for a while, because the girls will realize they can get up and come to you etc. and you will need to work with them to train them to stay in bed or at least stay in their room. That can be tiring! But it has to be done at some point, so do it now, since they are at a stage when the crib's no longer safe.