Those who have flown spirit - how does it work if I don't buy seats? It is truly randomly selected by the computer or is it more like open seating? It's my daughter's first time flying so she is a little uneasy about us being separated so I'm willing to pay for seats if that's best. She is 12, so not little. **Yes I know spirit sucks and yes I know we will pay for all extras, if you have anything negative to say - just keep scrolling. Please. Kindness costs nothing. **