We report on the isomerization dynamics of a family of substituted thiophene oligomers designed for the synthesis of soluble poly(alkylthiophene)s possessing a minimal coupling defect density. The data we report for 3’,4’-dibutyl-2,2’:5’,2"-terthiophene, 3",4"-dibutyl-2,2’:5’,2":5",2"’:5"’,2""-pentathiophene, and 3’,4’,3"",4""-tetrabutyl-2,2’:5’,2":5",2"’:5"’,2"":5"",2""’-sexithiophene indicate that the ground state isomerization barrier for all of these oligomers is on the order of 8 kcal/mol, with no discernible dependence on the length of the oligomer. For oligomer isomerization in the S-1 electronic state, we find that the isomerization barrier for both the pentathiophene and sexithiophene oligomer is similar to 5.2 kcal/mol, slightly larger than the value we reported previously for S-1 3’,4’-dibutyl-2,2’:5’,2"-terthiophene. Experimental data for both electronic states in these oligomers are in excellent agreement with semiempirical calculations using the PM3 parametrization.