Strava have updated their premium paid service (and renamed it to Summit) with a new model that splits the payment into three tiers so you can pick and pay for features that you do or do not need
The packs are detailed below
And the changes are discussed in more detail here
As mentioned for rowers I think most of the interest would be around the Analysis tier but also perhaps some of the custom goals and race analysis, I doubt many would want the beacon or heatmaps for on the river training!
Regarding the Analysis tier – I think this is probably the most useful but its worth noting that as blogged about before its possible to emulate a lot of what is included by using the free plugin StravistiX to pull your strava training data and provide fitness level, fatigue and race readiness, although obviously the official paid version has the benefit of being able to access the data from the mobile app rather than needing a PC