Sprint workouts for a distance guy coming to the pool world

I am coming to the pool full time after a long and fun run of triathlons and various multi sport events. Very excited about swimming a lot and love it. Problem is I have spent the last 20 years doing a lot of mind numbing threshold workouts. SO tired of that and anything over a 200 makes me want to head for the parking lot! I'm looking forward to becoming whatever kind of sprinter I can become. The great thing is I can and will swim no less than 5 days a week. Bad part is it will be by myself almost all the time I simply can't make the Masters practices and meet my family/work obligations. Would be great if anyone has any fun workout ideas since I won't be able to get them from a Masters coach. Thank you!