I was thinking Wittig reaction with benzaldehyde to get the cis isomer.
For the the trans I would have to go with cross-metathesis of styrene, but that's probably way beyond the scope of this question.
Other fancy alternatives:
1) Sonogashira coupling of phenyl acetylene and bromobenzene. Then you could reduce the alkene to get either the cis or the trans (Lindlar reduction and Li/NH
3 reduction, respectively. The Birch reduction might not work though).
2) Takai reaction on benzaldehyde to get trans-beta-iodostyrene, the a Suzuki coupling with phenyl boronic acid. (trans-stilbene) You could also make the iodostyrene from phenylacetlyene and the Schwartz reagent, quenching with iodine after the hydrozirconation.
3) Start with benzoin and reduce both carbonyls with NaBH
4 to get the meso diol, then eliminate to the alkene via the Corey-Winter reaction. (cis-stilbene)
4) McMurray coupling with benzaldehyde. (trans-stilbene)
5) Julia olefination with benzaldehyde and phenylbenzylsulfonate. (trans-stilbene)
6) I know you can convert trans-stilbene to cis-stilbene (or vice-versa!) by epoxidizing, adding lithium diphenylphosphide, and then methyl iodide. You end up losing diphenylmethylphosphine oxide in either case. Pretty cool, huh?