Verified answer

I would tend to agree with the muulti-effects processor... however, if you are looking for specific effects:

Distortion (although, with a decent amp, this is not needed. There are many guitarists that go direct to their amps and use the dirty setting/channel for their distortion.

Chorus to add a little lushness to the clean passages

Delay for the solos

Compressor to even out the rough edges

Don't forget to put the time based effects (delay, flanger, etc) in the effects loop of the amp, and the distortion, compressor, and such in front of the amp.

You would be better off with a multi effects processor. The quality is usually better and combining effects is much easier. They have come down considerably in price. One that comes to mind is the digitech RP350.