In Classical style projects, it is normal to use far more reverb than delay.
The real answer is: delay IS reverb, meaning both are linear, time-invariant filters that both do echoes (i.e. reflections in reverb terms). However, the way they are implemented is completely different from each other. Delay basically is the process of repeating the original signal exactly the way it comes in, with only altering the volume and the panning, and sometimes the maximum amount of "Echoes", while reverb is about choosing a pattern (often called 'plate', 'hall' or 'room') that has a big amount of complex "echoes" combined with frequency-related filtering.
To me, delay is more like a 'special effect' (which you probably don't use very much in classical music) while reverb is just useful when the orignal accoustics suck or you recorded classical music in the studio.
In my personal workflow: to add an accoustic impression to my classical recording: reverb. There is only one place where I really use delay: to delay support microphones so that their phase matches the phase of the main microphone. Say you are recording an orchestra, and you have a support microphone for the timpani to get a better sound of its attack. To actually make it work, the phase of this support microphone should be the same as the phase of the signal in the main microphones. This is not to be expected since the sound needs time to travel from the support mic to the main mic, so the support mic has to be delayed to get over this distance. (130 samples per meter when recording with 44k1 sampling rate, based on a sound travel speed of 340 m/s)
It depends on the project you are doing, really. My advice: don't pull out your delay plugins if your reverb plugins are doing the job well. These two types of plugins server different goals.