Parque Lleras would be fine, because most of your girl contact would be online, typically. They can come straight to your place without ever going to Parque Lleras anyway, but I would tend to think that if the cops are hassling anybody it would be the odd girl in the park looking to pick up stray gringos. It's a popular area because it's surrounded by eating and drinking establishments. . It's the safest and most gringo friendly area because English is more widely spoken there. I usually stay in Laureles which makes the girls happier because they travel less and it's cheaper to stay. It's easier for me because I speak fluent Spanish. Generally speaking if you're not an obnoxious tourist wearing hawaiian shirts and being loud with the girls then it's unlikely to be an issue barring a specific active crackdown, which I've never seen there. I mean, anyone with any idea in Medellin is getting girls online or directly in the bars (or the Hotel M).