Torres del Paine is a great hike. Hard but very rewarding. I think W and O Trail are going to be closed but if they are still open in April you can have a look. They are multi day trips and there are different packages from bringing everything yourself to renting finished tents. It's quite pricey however.
If going to Argentina is an option, El Chaltén Is a trekking Mekka that is well worth the visit. Bring USD or at least cash if going to El Chaltén, there is no ATM. It's also relatively expensive for Argentina.