I am listing below only chambers rated Lean or Tossup.
Alaska
Senate - Current Democrat 7, Republican 13, rated Lean R
House - Current Democrat 15, Republican 22, Other 2 (but under control of a coalition of moderate Republicans and Democrats), rated Lean R
Arizona
Senate - Current Democrat 13, Republican 17, rated Tossup
House - Current Democrat 29, Republican 31, rated Lean D
Arizona constitutes Democrats best opportunity to flip both Houses of a Legislature.
Florida
Senate - Current Democrat 17, Republican 23, rated Lean R
The Florida Senate features a particularly nasty race in District 9, which covers all of Seminole County and a sliver of Volusia County. The Republican incumbent is term limited and Democrat Patricia Sigman and Republican Jason Brodeur are running one of the nastiest races in the country, exceeding the nastiness of the Presidential race. Seminole County is trending purple and this could be a critical race in the battle for overall control of the Florida Senate.
Georgia
Senate - Current 21 Democrat, 36 Republican, rated Lean R
House - Current 74 Democrat, 105 Republican, rated Lean R
Iowa
House - Current 47 Democrat, 53 Republican, rated Tossup
Maine
Senate - Current 21 Democrat, 14 Republican, rated Lean D
Michigan
House - Current 51 Democrat, 58 Republican, rated Tossup
Minnesota
Senate - Current 32 Democrat, 35 Republican, rated Tossup
House - Current 75 Democrat, 59 Republican, rated Lean D
New Hampshire
Senate - Current 14 Democrat, 10 Republican, rated Lean D
House - Current 230 Democrat, 156 Republican, 1 other, rated Lean D
North Carolina
Senate - Current 21 Democrat, 29 Republican, rated Tossup
House - Current 55 Democrat, 65 Republican, Lean R
Pennsylvania
Senate - Current 21 Democrat, 28 Republican, 1 other, rated Lean R
House - Current 93 Democrat, 109 Republican, rated Tossup
Texas
House - Current 67 Democrat, 83 Republican, rated Lean R
I expected Democrats will net 200 to 300 State Legislative seats nationwide.