We found Viking were not exclusively seniors. We even had a young honeymoon couple on one!, but they are not for children certainly. As regards tipping, a few years ago Viking started giving out a separate envelope for the cruise host person. If you think about it, if everyone put something in that, then that person would walk off with thousands every week, at the expense of the galley maid who works just as hard. So we usually discard that envelope. On the trips we have done, the gratuity is in an anonymous envelope. we find the Americans want to know exactly how much a day they should put in, whilst the Brits seem to want to put a meaningful amount that reflects the wonderful service, but won't be dictated to by the company! We usually give a separate note to our cabin maid and maybe a favourite waiter who has been on hand all week to fill DH's glass up, lol. The good thing is that on cashless cruises, you don't have to worry about tipping all the time, unless you want to give a coin to the guide or bus driver etc.