What should I do with about $50k-$80k in spare cash at the moment? I have OCBC 365, UOB One Account and Citi Maxigain Account already and have maxed out the limits on these.

Just went by Citibank today to check my effective rate post being a Citibank Maxigain user for close to 2 years - effective interest rate now is 1.5% after maximizing step-up. Might consider other optinos already!

I suggest examining your end goal and objective. What would you like the cash to be used for? If it is to fund your retirement, you may consider moving beyond bonds/saving accounts and start to look at ETF/Unit trusts. (I presume you are not comfortable with the risks that equities have) These investment vehicles will grow wealth in the long run but are subject to risks, hence you also need to examine your risk appetite. If you are risk adverse, consider CPF SA top ups, and also annuities to complement your portfolio

If you are looking at growing the money for something in the near term (e.g. house purchase), then you might not want to take too much risk with it. In this case, bond funds and short term endowments/FDs might be better suited for your goal.

All of this is of course subject to ensuring that you have adequate and proper coverage so that in times of crisis such as critical illness and hospitalization, you do not have to liquidate your assets to pay the bills.

Other uses for the money could also be for SRS where you can enjoy tax relief and invest at the same time. The options are plenty and you should sit down with a consultant to look at all available options and then decide what might work for you.