If Solas turns out be our bi LI (IhopeIhopeIhope) I will romance him with a human rogue - probably an artificer/archer type. She'll be a bit of an ice queen - more interested in tinkering and learning than in romance. She'll find a kindred spirit in Solas. They won't clash much, since she'll be fascinated by all things magic and fade related, but she'll have a bit of violent streak that I could see him maybe disapproving of. Definitely a friendship-turns-romance situation.
My second playthrough will be with a free-spirited mage - most likely a necromancer. She'll end up with a crush-at-first-sight on Cullen, only to be dismayed by the fact that he's a Templar and pro-Chantry, etc. They'll definitely clash, and debate, but ultimately will come to respect each other, since their goals of helping people is the same.