I did it years ago, you have to get to Tigre early in the morning -- when you exit the main train station (not the tren de la costa one) you cross to the other side of the roundabout, over the bridge, and I believe the ticket counter is somewhere on your right (this was about 4 years ago, so they may have moved things a bit) -- if you take the morning boat you have about enough time for a lunch on the other side before taking the afternoon one back.
However, on the other side where the boat stops, if you felt like indulging yourself, you could go to the Four Seasons Carmelo for the night -- I haven't been but supposed to be very nice. There's really not much around there otherwise, unless things have really changed since I went.
However, on the other side where the boat stops, if you felt like indulging yourself, you could go to the Four Seasons Carmelo for the night -- I haven't been but supposed to be very nice. There's really not much around there otherwise, unless things have really changed since I went.