A simple model is presented for predicting the numerically "observed" sequence of ground states (GSS) of 2D electron droplets and quantum dots in strong magnetic fields. The model is based on the assumption that exchange and correlation in the 2D electron gas induce gaps in the lowest Landau level, producing a sub-Landau level (SLL) structure. The sequence of GSS results from filling the SLLs as the total angular momentum L is increased. Using the numerically "known" energies (for a few L) for N<or=6 we present a fit formula to predict, to within 2% accuracy, the GSs for higher N and L for which exact diagonalization results are unavailable. Typical results for N=6, 7 and 10 droplets are presented.