I love sampler quilts. It gives me variety in technique and overall what I'm doing. I get bored doing the same block over and over again. It does take more time but I'm never in a race to get a quilt done. I just enjoy the journey.
I've done them both ways - keeping the same color pallet and making them scrappy. This time of year I'm doing Row by Row and this year all my rows have the same color pallet but each are different. Last year with the seasons theme they were more different.