I love poplar too, especially for its streaks and lines, but it's not everyone's taste, and it doesn't stay pale for long (streaky or otherwise). It goes a nice honey colour.
I'm not convinced you'll like alder, if you can find it. It tends to be pretty yellow or orange, and someone recently told me that it's the only timber without a single use. Actually, it's favoured by clog makers I think. This hints are a wild tough interlocking grain that won't split, so you might not find it easy to work, unless you're turning. It grows beside rivers, so I suspect it doesn't season all that quickly.