Depends on the rest of the band, the style of songs you're doing and whether you're playing leads or chords. It also depends on your equipment...for instance are you going through the p.a. or using two amps? Also, how does going through the P.A. affect the vocals and are you talking about a home studio p.a. system or a club p.a.
It also depends on the venue and whether you're playing a small room or an auditorium.
Keep in mind that the sound you're hearing on your 4 track isn't just stereo ...it's a double tracked guitar.
Generally though, if you play live, the guitar is usually 99% mono for a rock band.
If you're at the level where you can afford a soundman and a P.A., you've gotta sit down over time during rehearsals and have him mix you like you'd sound in the studio. This could be anything from micing two amps in stereo or putting a separate feed through the p.a., applying effects and delay etc. and then working on the sets until each part is planned out in advance.