Something being deductible on federal is nowhere near the same as a tax credit. You don't get a tax credit for state/local taxes. You get a deduction (which doesn't apply under AMT). So, if you're in the 25% bracket, you can deduct your 10% state taxes, which reduces it from 25+10% to 25+10-(0.25*10).

California's 9.3% is the top regular marginal income tax rate. There is also an 8-10% state/local sales tax. There is no way around the analysis that California and New York are relatively high tax states compared to Nevada and Washington.