For romance, West End Show is hit or miss.
The real choice isn't 'see a show', it's which kind of night: a big, machine-tooled musical that's run for decades (Les Misérables at the Sondheim, Phantom marking 40 years, The Lion King at the Lyceum) or a sharper, riskier play in a gilded old house. Either way the staging is top-tier — but the venues are Victorian, so legroom and sightlines in the cheap seats can be rough.