I539 H4 COS vs L2 renewal

I am currently on L1B visa, which is up for renewal in Aug 2022. I also have an approved H1b and an approved i140. My spouse is on L2 and is working on L2 EAD. Considering the time (> 10months ) for processing i539s, I am wondering if I should go apply for a change of status to H1 for me, H4 and H4-EAD for my spouse - where they are effective from the last day of my current L1B visa. Would this be a better option for my wife’s continued employment, considering I can file this right away compared to my L1 extension, for which I can only apply in March 2022.

I think you are on right track and should file for COS for you and your spouse now.

I started the process on H4 COS and got to know from my attorney that although USCIS allows for filing of COS with no limit on how far the effective data could be, they apparently change the effective date to “upon approval” if the date is beyond 180 days in the future. So in this case, H4 COS is no better than doing L2 extension.