In "Unending", the last episode of the series, SG-1 gets stuck in a time dilation field aboard the Earth ship Odyssey, and a romance between Vala and Daniel finally comes to fruition.

Do Oneil and Carter get together?

Asked why the series never confirmed a relationship between Carter and O'Neill, producer Joseph Mallozzi stated in his blog, ... Pursuing any sort of relationship would have been inappropriate for both and would only have really been possible late in the series after Jack's retirement.

Does Vala like Daniel?

Unending - Trapped on board the Odyssey for some 50 years, Vala nearly goes crazy -- but finally ends up in a life-long relationship with Daniel.